Agreed, marksmen are still by far the most popular class in bot lane, it's just that now there are a handful of non-marksmen who go there as well (and who usually don't do as well as marksmen there anyway). This very much feels like the whole "ADC in 2k17" meme all over again, where a bunch of players overreacted because their class wasn't quite as overly strong as they were before. Nonetheless, this is apparently enough to warrant at least partially reverting the cost nerfs to crit marksman itemization, which will simply take us back to the drawing board.
I also agree that nerfing damage should be the priority here. I suspect one of the reasons people feel bad playing marksmen when they're not grossly overpowered is because nobody likes getting one-shot, and they'd rather have the option to burst down their opponents as well. To me, that's not a healthy approach, because it only further contributes to a game state where everyone deals far too much damage. If a squishy, persistent damage-based champion dies before they can make themselves useful (and stats show they still are useful even in this environment), then the issue isn't that these damage-dealers lack damage, but that the environment they're in has too much damage overall. It's not difficult to find a clip from 3+ years ago, and see how much lower damage was then, which is why it concerns me that Riot hasn't done more to remove excessive damage from League.