I can only speak to my own opinion, but I think there is something you have missed, here.
It's quite true that I played some 3.X and had nothing against the system at that time (although D&D constituted only a small proportion of my RPG playing from around 1980 to 2008). I am on record at the Hârn Forum "defending" 3.5 D&D as being a servicable Gamist system, which is to say the best of a fairly mediocre field, but not a system I would use for simulationist "dreaming play" or thematic "boot it into a story" play.
When 4E arrived, however, the situation changed. 4E is, for me, simply the best Gamist engine available. In that respect, it blew 3.X out of the water in the one region where 3.5 had advantages that I couldn't find bettered in other systems. Now, there is simply no water left for 3.5 to sail in, for me. It has nothing that it does well enough to warrant my selecting it to play. It's not that it is any worse than it was before, it's just that, for every style or "mode" of play, there is a system that I feel is superior enough to D&D 3.5 to make the choice a no-brainer.
A consequence of all this is that, if 5E turned out to be a really fine Simulationist engine, I might well consider it alongside 4E (as a Gamist engine). If it is a superior Gamist engine to 4E (which is old enough that I can see several possible improvements), I might switch to it. In neither of these cases, however, do I think the "one system to please them all" aim will have been met in the slightest. Nor, in fact, do I think it's possible for it to be met - but that's just an opinion.