What I meant was that some think that terraforming is possible now, if only we invested enough money in it. If that were the case, why has nobody ever thought of focusing our energy to fixing some environmental issues on our own planet first, before dragging an atmosphere towards another planet and the like. I'm not saying it should be attempted here first, I was talking about how far the required technology is from our level of development.
I agree that Biosphere2 like things (but working) would be an excellent approach for permanent bases on other planets, because they're self sustaining. Also without the idea of terraforming later, doing research to self sustaining closed habitats is a good thing. Even if we were only to find out that a closed habitiat has not got enough "critical mass" to be self sustainable, at least we would know that then.
I don't think the potential for terraforming should drive any decisions now. But if we're thinking about permanent bases outside the earth, thinking about ways to reduce the number of required cargo transports is a good idea. Things like Biosphere 2 that means.
But building a Biosphere2 like thing on Mars (once the concept is proven of course) is a bit beyond the current budget
.