Why aren't setup men paid better?

[Wynton]

Unless I'm mistaken, it seems that setup men are way undervalued and underpaid. Nowadays, the setup guys often pitch more innings than the closers and usually come into the game in more difficult situations. In fact, most managers don't like bringing in their closers in any situations except to start the last inning, before anyone is on base.

I guess the answer is purely statistics: saves are sexier than "holds." But if I were a gm, I would be placing at least as much importance on getting a reliable setup guy as getting a closer or even a 4th starter.