Why do you think Microsoft offers its email for free? Because they are nice guys?
One reason they do this is because the more you log into your email account, the more you click on msn's webpages-and thus the advertising space on their pages becomes more valuable.
Its not a case of one taking from them and they are getting nothing. They are also locking me into their other services, like Msn messenger. There are other chat software available, but Microsoft wants you to use theirs.
So I don't buy you argument, that since we have siphoned off them, they owe the users nothing.
If I go to a mall to go shopping, and I park my car in the malls lot, and when I come back the parking lot and all the cars are gone, can they say, well, what do you want, the parking was free. Your car was fine for a few hours, how long do you want us to protect you?