There is pressure from investors too. New MMO are often unstable from the financial point of view. Some of them start out strong but as the number of curious players drop rapidly, the investors will demand developers to do something about it. The investors don't really care about the core players of the game or how good the game is but rather about getting enough money for their investment as soon as possible. Large number of players tend to be an indicator of good returns to investments rather than core players' responds. So often the developers will have to resort to F2P to increase the number of players to calm the investors.
SE is spared from the pressure as they seem to let the developing team/director do whatever inspire them. I think they prefer a sure and steady income for a long time rather than a gamble of getting a big return or flop.