Whenever I see people advocate F2P, they always enthuse about how this will let them enjoy the game on their schedule. It's common to see points like, "I have the freedom to play for a couple nights, then go try something for a few weeks, then come back." And that's certainly true. It's a lot easier to dip in and out in a F2P game.
But consider the viewpoint of the poor raid leader. She absolutely does not want raiders who play for a couple nights, then disappear for a few weeks, then come back. She wants people who play on a regular schedule.
By making raids subscriber-only, The Old Republic is potentially allowing people to signal their commitment to the game. That they will log in and play regularly enough that a subscription is a good value to them. That they will make the type of dependable raiders that a raid needs.
I fully expect the pool of people able to raid will shrink, perhaps even shrink greatly. But the people left in the pool should be more dedicated, and could end up forming steadier guilds.
To take a larger view, I wonder if this extends to community in general. Community bonds are formed through repetition. To joining the group, and seeing the same people every time the group meets. You know, you log into your guild, and the same people are playing, and they greet you and you greet them.
But with F2P, and everyone logging in at random, will the same bonds form? Or will what passes for community end up being weaker.
I guess I don't really see the point in playing an MMO if that community isn't there, if you don't see the same faces whenever you log in. You may as well play a normal multiplayer game where everyone is anonymous.
Perhaps by abandoning the subscription model, MMOs are weakening what makes them special.