Yes personally I believe good system design is balancing the conflicting demands of:
(a) Power Balance, you should have at least an attempt of people doing different builds reaching a compareable power balance in the end. One of the reasons why I dislike TES so much is because that this was clearly never considered at all, before Skyrim and the new re-relase of Oblivion.
(b) Width, you want to give people as many options to play a character as possible. For example in classbased systems, you want not just a Fighter class, but also for example a Paladin, an Anti-Paladin of sorts, a Ranger, and whatever other concepts you could come up with. And you want subclasses and feats. In skillbased systems, you can only really work with feats. Again in TES you can play a master-of-everything and nothing stops you from doing so at all.
(c) Depth. No matter how your character is built, a character should have multiple avenues to approach a situation, and should be able to raise their efficiency by carefully weighting their options. This again was screwed up by TES by creating the most boring and unimaginative magic system I've encountered in any fantasy game.
Of course a balance of power is easiest to maintain if everyone plays the exact same character. But width and depth both require a complexity, if not of the system, but then of the possible decisions to derive from that system.
One of the reasons why I'm so impressed by D&D5 is that it manages to reach all these three goals while being very simple at the core. AD&D for example was much more complex, full of tables that you only could memorize, without allowing this great variation in characters one can create.
