I think the point is that somebody has to pay it. You pay 50 bucks for the game, that pays for them to develop it and provide you with the game, pay the salaries, expenses, ect.. - and yes even make a profit (hopefully).
The MMO part of it, the monthy subscription charges, or however it is payed for is to keep the servers running and keep paying the staff that is necessary to keep it working (and yes, again perhaps making some profit). Bandwidth costs money, keeping the servers running costs money, people costs money, and yes they make games to make a profit. If you do not have a renewable source of income such as a monthly fee, then you cannot keep up with the ongoing costs because eventually that initial 50 bucks you spent will get used up and there will be nothing left to pay for the ongoing expenses.
They said they will be supporting the ongoing costs with selling influence or other methods instead of a monthly fee. A game like this probably has very low overhead compared to a typical MMORPG which is why the monthly fee is needed. If WoW for example didn't charge $15 a month, it would no longer exist.