I believe in fees 100%.
Have you ever played a good MMORPG? How could a game like Everquest or Asheron's Call stay online if all those people payed $40 for the game, then played on their expensive servers for 4-5 years? They would be totally dependent on new users, which wouldn't be near enough money to pay for the bandwidth alone.
Fees also keep the crowd more mature. It limits the hacks and exploits as well. No one wants to have their their account deleted after they have poored that much money into it. (Although people still do

)
Also, fees keep the game up to date, by adding content, and preventing exploits and hacks, in the form of patches. How many patches have come out for Bloodrayne (single player only game)? None.
A point to add on your defense though, Diablo 2 is a great example of a MMORPG (I know that's a big streatch

), where there are no fees and it is constantly updated with patches. Then again, this is Blizzard we are talking about. Of course, hacks are still rampant...