We don't need to attract more casuals to play RPGs. The hobby is booming. Today, in 2018, D&D has as wide a reach as it has ever had. Tabletop gaming is several years into a popularity explosion. It has never been easier to learn about D&D or to find a group.
Where we do need more work is in making it easier for DMs. D&D 5E is still a relatively complex game - more complex than 90 per cent of boardgames. And from what I've seen of the boom we're experiencing, most new players are not especially interested in the mechanics. They'll roll the type of dice you tell them, and mark off the numbers on their character sheet. But they aren't taking the books home and reading them. They aren't digging into the tactical actions available in combat, or brushing up on spells and feats.
That leaves all that work, the management of the mechanics at the table, up to the DM. And in many cases, these DMs are new themselves. So not only do they need to learn a complex game, prepare for the adventure, run all the NPCs, do their dramatic voices, and run the session, they have to babysit half the players at the table.
WotC could make things a lot easier. They could condense the mechanics of the game onto 2 page summary sheets. They could offer all kinds of play aids around running combat, levelling up, and running encounters. But for reasons which I don't really understand, they don't. Play aids are like a blind spot in RPG publishing.