Just to answer #4, IME the median player will grumble a bit but is so desperate to play D&D/RPGs - there is a big shortage of GMs compared to players - that they will give the game a try, in order to have a chance to play at all.

Yes.  You can mass produce "ok" game sessions.  They'll scratch some itches, both player and GM.  They'll have their moments of fun.  Hop on, follow the formula, and enjoy, like an occasionally droll sitcom. 

You can't mass produce good game sessions.  And I don't even mean "good" in the sense of excellent, great, really inspiring, etc.  I mean simply 'good" in the sense of sustained, interesting, hobby-growing, keep doing it and having fun year after year.  It's not a high bar, but it isn't a low one either.  It requires some effort and attention from a GM that cares. 

The average one I've met is generally somewhat nerdy and already knew about D&D or knows about it through pop culture and got invited into it by a friend. They generally play it to socialize or because they played it, or wanted to play it, as a kid and are feeling nostalgic. I think most wouldn't really object to an OSR ruleset or another rpg. The ability to make a "special snowflake character" generally wears off pretty quickly. Most just want an excuse to spend time with their friends or blow off steam.

I suppose the obvious question is "which street?" The way I see it, there are a few pretty huge generational splits in D&D, less determined by actual age group than by when they got into the hobby. Outside of the OSR, the most vocal players online are the ones who got into the game in the last 5 or so years, basically the 5e generation. I'm not sure how representative of the average they are, though. Lots of the older players just quietly run their home or VTT games without getting involved in the e-drama around the hobby. It's just that the OSR people are highly motivated, and the nu-schoolers are of prime social-media age, so those two groups make up the online conversation.

This gives me an excuse to expound on one of my pet theories, though, so I will. I think you can tell quite a lot about a player by looking at what their fictional influences are. These set a person's expectations about what fantasy should be like, as well as what kind of tone and structure they gravitate to in their games.

The first generation of D&D players, that got into it in the 70s and 80s seem to be primarily influenced by classic fantasy literature (Howard, Leiber, Moorcock, Anderson, Zelazny etc), as well as by 80s fantasy films like Krull, Conan and Beastmaster. So the games they made --and are still making-- are all about recreating that gritty, sleazy sword & sorcery tone.

My own generation of players that joined the hobby in the 90s and early 00s were heavily influenced by the fiction produced by that first generation of gamers. So books by Weiss & Hickman, R.A. Salvatore and Ed Greenwood, as well as computer games like Diablo, Baldur's Gate, Planescape: Torment and Dragon Age, and the Lord of the Rings movies. Pretty much the peak period for that kind of "elves, dwarves and wizards" high fantasy that D&D is associated with, and that is very much the kind of game that 2nd and 3rd edition are. 

The late 00s and early teens seem to be a bit of a dead zone for people getting into the hobby, what with the failure of 4th edition and all. As for the current generation that got into the game in the teens and up to the present, I'm a bit out of touch, but their chief influences seem to be things like Harry Potter, DC/Marvel movies, anime, and TV shows like Adventure Time, Supernatural and Avatar: the Last Airbender. Mostly pretty light fare, with an emphasis on colorful characters and flashy powers. I think that maps pretty cleanly onto the culture surrounding 5th edition.

Of course, these are broad generalizations. There are outliers in every generation, and lots of crossover between generations, but I think the broad trend runs true.

To tell an anecdote, my running group of mostly grouchy old boomers has one newer, younger player in it, who incidentally spends a fair bit of time complaining about the wimpy nu-schoolers in his other gaming group. The guy is a second-generation D&D player who grew up hearing about the game from his dad. Outside of playing TRPGs, he's into Dark Souls and old-school CRPGs. When he wanted to run Traveller, he went digging through 60s and 70s sci fi movies and books for inspiration. I would guess that's fairly typical for the profile of those newer players that are willing to step out of the 5e comfort zone.

Think you overstate the case, for a very simple reason:  Players don't really know what they want.  This is a specific case of the wider phenomenon that customers don't know what they want. 

Oh yeah, they think they know what they want.  Having experienced something, they can tell you quite accurately that they did or did not enjoy it, and even roughly how much. 

So I've found it usually quite productive to give players what they need.  Do that, and the ones that are going to enjoy the hobby will find themselves enjoying it.  One way or the other, since there are several different way to enjoy it. 

Had a session a few months ago run mostly old school style.  (It was my system, not D&D, but that doesn't matter.)  Point being, afterwards there were several comments and agreements about how fun it was, from players ranging from Gen Z and up (about 25 years range of ages).  Specifically, they commented on, "It was hard!  Felt like we could really lose.  So and so almost died, twice!" and so on.  They only avoided two deaths because of luck in the rolls (out on the table for all to see), and they knew it.  That was 8 players.  You could asked them all what they "wanted" before the session started, and I guarantee no more than 1 or 2 of them would have even hinted at wanting what they got.

The average person on the street, even though there really is no such animal, is putty when it comes to these kinds of questions.  Give them a good game, and the ones built to enjoy it will appreciate it.

Right. From the "average player perspective" this is true.

But "giving them that good time" requires a GM. And while it might be that the 5e D&D Experience is presumed to be running one of their pre-fabricated adventure paths... I see those players and GM's dropping from the hobby unless they have a GM that really does a good job delivering it but even then, that GM will need to strike out on their own to make better content.

They have to *want* to GM, like all of us did when we were done running all the original modules to death. At some point, you have to develop the desire to go further. I mean when you look at the modern stuff 5e puts out, there are much larger inconsistencies in their settings vs. 1e and 2e's original settings and how they were produced. I'll do you one further - when WotC took over, their content made the established settings *more* incoherent. The Freakshow Party Effect is a direct example of where the assumed rules overlay the setting conceits.

When 5e tee'd up Spelljammer - at least here the modern conception of "anything goes" would have the perfect setting in which to exemplify itself, and still these clowns dropped the ball.

I see a lot of these D&D players falling out of the hobby faster than it happened in previous generations. But conversely, many will stay in the hobby, outside of D&D, because many of them will look at the landscape of TTRPG's and find new homes. To what degree this happens, I have no idea. It's just a suspicion. Of course this puts the onus on GM's and non-D&D game companies to do that outreach.

Old D&D was about the game itself, and playing to find out what happens.  More and more, modern D&D is all about the player characters.  DMs are encouraged to root for the players, and become their cheerleader.  It's just odd.