Nobody is casting wish at level 2, and fighters scale better at DPR than any other class - they are the hardest hitting class in the game at level 20 (and pretty great at level 2, for that matter). Lack of damage dealing is not a fighter problem, and if you buff it, then what do you do with rogues, barbarians, monks, etc.? The general complaint about fighters is that they are great at taking and dealing damage but too one dimensional, especially in other aspects of play than combat.
When people talk about "power" and high level magic like wish, they aren't really talking about damage dealing, they are talking about the ability to alter the parameters of a situation. Increasing the fighter's DPR won't end those complaints, because it isn't the issue.