Well, Raw, while it may not be right -- it also goes well beyond the comics industry. It's done in the toy industry, the computer game industry, the roleplaying game industry, and virtually anyplace that uses outside freelancers to create new concepts. Like you said, it is the price of admission -- you use the money you get from work for hire to pay your bills, so you can use your spare time to create your own stuff and maybe have that see the light of day.
As I've said, I did work for hire for years -- and though I don't own my properties, it gave me a decent bibliography that I can use to try to sell my own concepts to someone and try to get a piece of the pie. Good or bad, that's the way the rules of the game are -- the trick is to learn how to use them to your advantage.