Should the player model reflect the class? In other words, Warriors should be built for strength, rogues for athletics, and spell casters, basic physical fitness. Remember that we are adventurers and if we can't survive the outdoors, then we should have a body to reflect our ability to be able to rough it out. I don't care how many spells I can fling, if I can't walk a few miles in the wilderness, I shouldn't have left magical university.
If you're building off of a generalization for each class sure, but playing with flaws, even perceived ones, can add immersion to people. Take Raistlin Majere, granted he's from Dragonlance and not FR, but he was notoriously frail to the point of not easily walking a few miles in the wilderness.
To use a non-established character example you could easily make a Dex based Fighter who isn't going to necessarily be swole. If you're going with Eldritch Knight they could even be Int focused and look frail compared to other Fighters. Now granted not everyone is going to want that, but having some control over our body type would allow people to play around more with different feeling characters and attach ideas to them more readily. Classes are only meant to be a general idea of the characters background, it doesn't necessarily reflect what they may look like.
For me personally I hope that we can at least have a few basic body types, as I'm rather skinny and like to make characters like that. Everyone has different ideas though, and the more choices we have to bring our characters to life the better, at least in my opinion.
