Parmandur
Book-Friend, he/him
I mean, the majority of people playing are new: veterans of any previous edition are a minority by now. Heck, a significant percentage of players weren't even born yet when 4E came out.Mearls was trying to woo the OSR community, including some of its most unsavory bunch, during the D&D Next design and playtest phases. These people gave their input, Mearls appeased them, and then they promptly ignored 5e and continued playing their preferred OSR games. But these aren't the people who are now playing 5e D&D in mass numbers. Most of the D&D "veterans" who play 5e are likely WotC-era players (e.g., 3e D&D, Pathfinder 1e, and 4e D&D) at this point.
That seems sensible. Hopefully it would also include some sore spots that come up in feedback surveys as well.
I do think that the game would benefit from greater character customization at 1st level. For example, if you know that your character will be an arcane trickster, it can feel sucky (IME) to not jump into that character concept immediately, instead having to wait until 3rd level before you can even start casting cantrips. However, if a cantrip or two was tucked away in, for example, a Background (e.g., Arcane Apprentice), then that can go a LONG WAY to helping some characters get their feet wet into the concept. I do wish that Backgrounds had more "teeth" to them. I'm undecided if feats are the best way to go about it, but Pathfinder 2 does include feats as part of their Backgrounds.

I think bringing all Subclass choices to Level 1 would be good, but I think it's too early to say if they are looking at such sizeable change. I think it could be done while essentially maintaining backwards compatibility (still allowing old Adventures to work, etc.).