If you were dictator you may be able to do that. I don't disagree, but see it as a moot point. All we need are one or two years of the tax returns to see how the person lives, what they donate, etc. You get no more information from still more tax returns.
Shoot, I don't claim most of my donations, my tax returns aren't even an accurate reflection of that.
Somebody at the IRS has looked carefully at the returns of a Presidential candidate, we'd know if there was something truly problematic. That they release any more than the last year's return as they are running is amazing to me.