This is something that I only realized recentl when trying to sell players to fill the bank account that has gone from almost zero to minus a million (Euros, mind you) in less than a half year during playing in Germany's third division:
The main advantage of getting rid of those is that you're saving their wages.. and that's it. Really, the average value of a player in my squad is less than ten thousand Euros, while in reality it looks like this:
http://www.transfermarkt.de/de/verein/64/sv07elversberg...icht/startseite.html
For a game that's been praised for it's realistic depiction of football, there's quite a few gaps worth filling it seems.

I'm in trouble with my bank account now though, although I've heard that isn't so much an issue in the FM series anyway.