Is it something new? I haven't noticed much of an evolution one way or another over the years.
I'm not sure I can put a finger on it (hell, maybe its even a perspective of rose colored glasses from days gone by). I noticed it when I got into 3.5 DnD after not playing for several years and it
seems to have deteriorated even since then. I've also diversified my interests in RPGs as well, so I've picked up a ton of new books over the last two years.
I owned the 4e ruleset for a few months, having bought a release printing. That was attrocious, especially in the powers section I noted. I've heard second-hand the editing in the new WFRP is bad as well. I could probably find some more examples when I get home and can glance over my collection.