My experience tells me you're wrong in your assumptions. When any character can be anuyhing without problems or weaknesses, the choices become meaningless and every players, and I mean every single one of them will fall in the optimization traps. I have seen it so often that anything said won't make me change my mind. Hell!!! I even fell in this trap my self in Vampire the Masquerade and Heroes.
Having to find ways to make an underdogs with fixed abilities is way more rewarding and memorable. The halfling barb was a thing to behold exactly because it was a halfling barb with the standard array. All its ASI went to strength and the little bugger was surprisingly efficient. But with floating ASI, no surprise, no cost, no sacrifice would have been required. The halfling would have simply been an other optimized barbarian.
I have nothing about optimization. It is a good thing most of the time. But when optimization makes it that what would be a strange character concept just becomes a simple skin for an optimized character type... I simply feel that the choice is just a make up, a simple mask that has been put on to give a funny look on your character. And believe me, funny look don't strike anyone as memorable. They are forgotten quickly.
But when your choices involve actual sacrifices in effectiveness, people remember the character for life.
You make it sound as if optimizing is a bad thing.