(I recognize the one good argument in favor of random rolls, which you describe, but it's just not worth the ridiculous gap in effectiveness that usually results when a group rolls. Speaking for myself, I actually don't need random help to create and play fun concepts.)
"Need" is such a strong word. I dislike it intensely in this context, as the implication is kind of insulting.
Would my player have been able to come up with an interesting concept using point-buy? Sure. The guy doesn't "need" the dice to create a cool concept - he's not creativity-challenged, or something. However, taking inspiration from something outside yourself can lead to avenues (and occasionally heights) you'd not go to on your own.
I mean, otherwise, the haiku and sonnet wouldn't be nearly so cool as they are - structure or restrictions can aid creativity, rather than hinder it.