Re: Between that
I think the general observation to be made here is that a lot of politically active people are also quite naïve. The world works in a certain way, and contains people who are saintly altruistic and conscientious and also complete selfish arseholes, and everyone else in between.
Utopian ideals are a noble goal, but it is not possible to flip a switch and go from where we are now to peace and equality for all, the best we can do is gradual change, and to push to make that change happen as fast as possible.
It's worth noting, as well, that although for some, a Marxist world is their idea of Utopia, it's certainly not a view shared by most on the left, in the same way that a corporatist world with all the wealth hoarded by a very few individuals is not the idea of Heaven for most on the right.
As for environmentalism? Well, it makes sense that we should make best endeavours to not cause our own extinction. Most people will agree that AGW and pollution are real problems that we genuinely need to tackle, although you'll find plenty of whackjobs hiding under rocks if you go looking for them who will argue otherwise, until their elderly parents start shouting at them to get out of the basement and find a job.
Environmentalism naturally sits somewhere to the left of the "political spectrum", so it's hardly surprising to find some proper radical Marxist types extolling its virtues, however, I think you'll find that the number of genuine full-on Marxists is very small, and the vast majority of leftists sit comfortably in the "lets be reasonable" ground of the centre-left, which is also the home ground of environmental concerns.
Biting the hand that feeds IT
