I'll talk about myself here. I've thought about applying before and others have suggested that I should, but it's not something I feel would be a great fit for me now. (I would never assume I would be accepted, of course.)
One
part of the issue for me is time. Between working full time, family, and various other obligations and activities I end up playing FT in sporadic bits. Maybe an hour one day, nothing the next, 30 minutes after that... Time spent on the forum, which is not insignificant in my case, will naturally cut into that. And then there is the big bombshell that FT is not my entire life and I spend probably more "leisure time" on other things.
Oh, sure, players all understand that GMs are busy and might not be able to respond to something right away, right?
Now, paying GMs or not is one issue, but regardless of that vasinta hit it on the head that the game needs "a stable team" to help it. Me? I don't feel I have time for it if I were to apply and we're to be accepted (which I cannot stress enough I would never assume to be the case). I do not believe I could offer that stability.
Sure, there could be a "part-time" GM. Help when you can help and so on. Since I'm just talking about myself, that's where I point out that time is just one part, which was even underlined.
Now, I'm not intending to be all conceited here like my thoughts have any bearing on anything else like I'm super important, but it's just commentary about one person that could be somewhat similar to what others think.
Old soldiers never die, they just fade away.