Why do people keep bringing this up? I hardly can imagine optional model, it's usually either sub or not. Some may view payed subscription as good business model after WoW success, but it completely alienates pretty significant slice of players, making game unappealing for them. For example, I'm adult person, I have a job, I have money to spend on games, but since I have a budget, I still have to calculate how much I can spend on what. For average adult person, time to game cannot be as consistent as someone who is at school, maybe university or retired. Sometimes I get to play a whole week, sometimes I can barely find an hour to spend with my hobbies, sometimes I need to travel, and packing gaming laptop isn't sound to me (because obviously laptops are bad for gaming in general), plus on these trips one can be busy enough not to have time to play at all.
There are handful of different online games I would be glad to play, but if I buy monthly subscription and then either won't have a time to play for few weeks or will have to travel, it means I payed for nothing. How is that fair? I really don't want same thing happenning for Elite. And as folks mentioned, if you really want to be a supporter, buying set amount of in-game currency will be same thing for you as paying for subscription, but still a lot more flexible and fair on all accounts, no?