And that's the problem right there. We all look at our small pools of players and our own thoughts. And if we feel like 3.5 did it better in some ways, we then start to go "well clearly 5e is just not up to par", that is simply an uninformed "feeling" not backed with any statistical rigor.This is purely anecdotal
We don't have access to the large amount of data WOTC has. I mean if WOTC thought based on their polling and surveys and market research that adding in more 3.5e mechanics would make the game better they would probably be playtesting that right now..... its a win win for them, if those changes were more popular AND made more changes, that gives double incentive for people to buy the new wave of books.
So what is more likely:
That WOTC did all this market research which told them nothing, threw out the old editions, made 5e, and got "crazy lucky" with the timing of things.
OR
WOTC did that market research, used it to create a game thats resonated with a larger playerbase, and got fortunate with the timing and other factors to create the modern phenomena that we see now