Well, “less is more” is very much a core belief of mine in picking apart this franchise. I don’t think it’s so much a matter of ‘more clearly delineated roles,’ because most Pokémon do have that down pretty well anyway; the problem is how easy it is to be outclassed by things that have a similar roles, and making moves less widely available might help with that. The presence of TMs in some ways is a little unfortunate, because the increasing ease with which we’ve been able to teach those moves over the years (first breeding to recycle them, then just outright reusable TMs) sort of devalues the Pokémon lucky enough to actually get some of those awesome moves in their level-up lists. Panpour is the only Pokémon in the game who naturally learns Scald! Did you know that? I sure didn’t. Do you care? I sure don’t, because just about every other Water Pokémon who isn’t also an Ice-type gets it too!
This is sort of part of the messed-up incomplete charm of the original Red and Blue – a lot of Pokémon just don’t have access to very good techniques, and with single-use TMs and no breeding, you have to think long and hard about what to do with those precious discs (well… except for the part where the games are so horribly glitchy that you can basically turn them inside out and make them your bitches without any special equipment or expertise whatsoever, but I’m a theoretical kind of guy, so sue me). It was a little unfortunate that this ‘feature’ of Red and Blue came with little, if any, thought for game balance (something that I doubt was a major fixture in Game Freak’s mind at the time), so some of its victims are Pokémon like poor Sandslash, who will never get any Ground attacks at all unless you spend your Earthquake TM on him, and remains lacklustre even if you do. Maybe today, though, it’d be a neat balancing factor on a really powerful Ground-type like (say) Excadrill if Game Freak were willing to arbitrarily say “yeah no Earthquake for you lol use the goddamn signature move we gave you” (and, in that particular case, it encourages Excadrill to be more like Excadrill too). Might also give more of a point to some moves that look and sound cool but just have no reason to be used, ever, like Aurora Beam – every Pokémon that learns it also gets Ice Beam, with the exception of one (Xerneas, who has better things to do with his time).
On the other hand, can you imagine the backlash from the fanbase if that were implemented in a future game and hundreds of Pokémon lost many of their best tricks? People get annoyed enough by the obsolescence of move tutors and the occasional TM. I sure wouldn’t want to be the one to announce that. Accumulating more and more skills and abilities for Pokémon just seems to be the way this franchise typically operates, and I don’t think that’s likely to change any time soon, whatever I might think of it.