[...]seeing how most religions actually promote things that are altruistic and benefitial to their communities
So, hating gays, denying evolution, disparaging women, opposing abortion and promoting intolerance are good and altruistic? Come over the border, listen to our priests and you'll see that. Organized religions are selling a promise even more vague and illusory than Roberts, demanding money, time and public endorsement in return. If they were treated like regular businesses, many of their strategies would be on low end of the ethics scale. They do preach some useful things and run charities (though many "fat cats" have a foundation of their own, too), but that are about the only redeeming qualities.
If you got rid of all the charlatans in Catholicism, you'd be left with the monks, a handful of mid and low level clergymen and the current Pope. Most of these charlatans do believe in what they preach, but that doesn't stop them from being greedy bastards (yay for hypocrisy!). These days, religion is peddled like any other product. This applies more to "new age" religions than the old ones (which at least pretend they aren't), but applies nonetheless.
Predatory marketing strategies are bad, no matter why you pursue them. Selling people their own dreams is never a moral or ethical choice for a business to make, no matter how deeply convinced people are that what they're doing is right.
They're not selling people their own dreams, they're selling them Roberts' dream. That people appear to have been dreaming about the same thing as him is a factor in their success, but Roberts wanted this as far back as the time he made Freelancer. He himself believes that this dream is possible to achieve. Whether this is true is not certain (and I don't think so), but the important thing is that Roberts didn't start this with the expectation that the project will peter out and he'll be able to run off with the money. He could've easily done it long ago instead of sinking that money back into this juggernaut, if that was the case. You may question his judgement, but not his intentions.
Also, any scheme in which you pre-purchase something is a gamble. If you pre-purchase the latest CoD, you also buy a promise of a working game with gameplay you'll actually like. Granted, in their case odds are much better, but the principle is the same. Roberts is promising that various things will be "fun", but that's a rather vague thing which means different things for different people. Indeed, a quite likely end result for SC is a game that technically does most things it promised, but just isn't terribly fun to play. Maybe there are people out there who
like the buggy mess SC (just check out Kerbal Space Program. Hang out long enough on the forum and you'll run into someone who complains about
straight bugfixes because he learned how to exploit a particular bug).
"Roberts et al are taking advantage of people's generosity" is the nice way to put it. What is actually happening is that they're taking advantage of people's gullibility. Just because people let themselves be charmed into throwing money at this project doesn't mean that what CIG is doing is morally right.
TBH, I think much more of generous people than gullible ones. A generous person might give them money against his better judgement because he likes making people happy. A gullible person would give them money because he has no better judgement. Take a guess which one is more likely to be intelligent.