It would be nice if D&D was more open to "organic development". That you could easily just acquire a new ability because it makes sense to do so, as part of the story, and not hamstring yourself by doing so. Or that you didn't need to make decisions about your future when you lack a real life crystal ball.
A good example of this was when 3e changed multiclassing. So you could play a Fighter who starts to become curious about magic, and have long conversations with the party Wizard while taking watches. And even, under their tutelage, take a level of Wizard yourself!
But this doesn't appreciatively help you be a Fighter, and you're now a very poor Wizard, with no synergy between your roles, unless you planned for this levels in advance, and took the right Feats to become an Eldritch Knight or whatever.
OTOH, the AD&D approach isn't much better, where you also have to make the choice about whether or not to be a multiclassed character at level 1 (even with dual-classing, you need to make sure you have high numbers in certain ability scores to even attempt it!), and of course, you also need to be careful about your choice of race as well (unless you're playing in Lankhmar or something).
2e's Kits are much the same way; you are asked to adopt them at level 1. Even weapon specialization requires some level of foresight (knowing that one day, a +4 bastard sword might appear in the campaign) or just gaming the system by selecting a longsword (knowing full well that not only is a magical glaive-guisarme highly unlikely to appear save by DM fiat, but the magic item tables limit it to +3 anyways!).
And while it's not really a 1e concern, the rate at which you gain Non-Weapon Proficiencies in 2e is nearly criminal; your Fighter could spend an extended amount of time at sea at level 4, but have to wait until level 6 to have a chance to gain Seamanship!
1e's "everything is an ability check" approach (at least until the later books, like Oriental Adventures) was definitely better for this, but the level-based "stay in your lane" system does prevent some kinds of development.
For example, your Half-Elven Fighter/Thief can't suddenly, upon encountering an actual deity, suddenly decide to change their ways and devote themselves to becoming a Cleric; they missed that boat in character creation!
I'm not saying this is all bad; I generally prefer level-based systems over things like GURPS or OWOD, where you can accidentally overspecialize or build your character to be unable to participate in many adventures; it's nice to say "level x characters have this baseline of ability".
It's just something you have to accept in D&D; there are choices that are locked in for you at character creation that can affect you down the road, whether you see them or not. No version of the game is truly better or worse in this respect, IMO.