Have to reach through this thread a little more, but OP, having also been someone who recently (about six months ago) started watching anime again after quite literally a near 15-year hiatus, I've definitely felt a change in the nature/quality/target demographic for shows.
My Planetside outfit basically has an anime night (Tuesday nights) where we watch seven shows a week. The first three shows are series that we vote on and then watch beginning to end, and I have them split into three blocks (Pre-2000, 2000-2009, 2010-Present). After this, we have four 'weekly vote blocks', where three shows go up for vote each week, with a 'winner stays' system (e.g. if Show A wins Block 1, then Show A + two new shows are up for vote in Block 1 the next week). We've got a pretty curated list of about 250 shows that I 'randomly' pick week to week.
This format has allowed us to get through a few shows, especially newer shows (we've finished two 2010-Present shows end to end - Death Parade and Kids on the Slope, both of which I really liked, and I've picked up a large smattering of the first 3-4 episodes of some other shows).
The demographic that shows up is decidedly younger than I am - I think the oldest person other than me that is a 'regular' is about 22 - with tastes that tend to be a little different than mine (though they do appreciate the 'classics'), and we've had discussions on topics very similar to the one you discuss in your OP. My feeling so far has been the same as yours - which, based on the shows we watch, seems to have started slightly around 2008 or 2009 - and it's one the folks I watch with have started to echo as we watch a wide variety of shows. I've still found a fair number of shows I like in the past few years... but then we throw something like Trigun (1998), Berserk (1997) or Sayonara, Zetsubou Sensei (2007) into the rotation and they seem far more likely to be repeat winners.
One thing I do actually like about more recent shows is that they seem to be shorter more often (12, 13 episodes) and all killer, no filler. We're currently 24 episodes into Nadia (the first winner in the pre-2000s block) and every time an episode shows up that just seems to be eating up a week I die a little inside since I know we still have another four months to go. The shorter runs, however, make it a lot easier to ride a show out if it's supposed to be good and you waste less time overall if it's just OK.
Edit: For reference, here's a list of the shows that won votes during our run and how the folks watching felt about them:
https://pastebin.com/tfnfrwrL