I think there are some valid points being made, but I‘ve got a different perspective.
1) a lot of players I’ve seen habitually playing wizards (and to a lesser extent, the other full casters) often play cookie cutter characters. One guy I know played essentially the same wizard build from 1Ed through 3.5Ed, and only changed in 4Ed because the core options he preferred had changed. (He still played a wizard, though.) Every mage PC he played, he played the same way. Watching him play a mage was as predictable as watching Tic-Tac-Toe. I would not be surprised to find people in this thread being able to predict his spell lists.
Over the same period of time, I played single-classed and multiclassed generalist wizards, Illusionists, Transmuters, Enchanters, Conjurors and Diviners. (And other stuff as well.) Even within a given caster type, no two PCs had the same spell list.
2) Some of the options that started popping up as the game evolved were shunned by players, which led to designers orphaning them. Example: I loved the Feats in 3.XEd that granted spell-like abilities: some mimicked particular spells, some allowed alternative uses for spell energy, and the Reserve Feats. I’ve used all three types in play- all were fun, and definitely broke the PCs’ feel and playstyle away from the stereotypes. But none were particularly powerful, and some were even capped. Because of that, they were largely ignored in favor of the Metamagic and Item Creation feats. As a result, most of those types of Feats disappeared, not just in subsequent editions, but even in later products within 3.XEd.
(I, for one, was genuinely disappointed when Reserve feats were abandoned right after they were introduced.)