The only problem I could see would be if Amazon sales were cannibalizing other avenues, leading to a lower overall profit. But I'm sure even if this is the case, Amazon's volume more than makes up for it.

So yes, this rant is pretty pointless. This is the way every marketplace works nowadays: iTunes or Themeforest are the same. They take a big cut and reinvest the profits in marketing and advertising to grow the marketplace larger (and thus generate more profits for you in the long run).