Ok well, first of all, Evolution RTS is free. Second of all, it is NOT gpl.
It is however, open source in the fact that you can view it here: http://redmine.evolutionrts.info
Third, the text on the games page is rather outdated. Unfortunate, but I didn't realize it.
Missions were an experiment that I tried way back in the day. The missions were objectives set out in an online game. It was entertaining, but the results were entirely unpredictable and doing them never turned out that well (at least in my opinion). There is talk of resurrecting the missions, but atm all it is, is talk. I would like to, once we go to final release, but thats in the future.
We are a small team, and as such we can only do so much, so fast. The main thing we are working on at the moment is finishing the game.
The goals are the same as any other rts game. To be fun, ultimately entertaining, provide strategy and tactics, and provide a rewarding experience for the player. The pre-alpha is available, and is quite playable. Even the svn install can be played online.
Licensing annoyances? I assume you are referring to the fact that it is original content vs inspired content or blatant "theft" (keep in mind, there is a reason why that word is in quotes), in which case, yes, exactly. There have been too many contributors over the years to accurately name them all (Pretty much all the bigwigs around here have contributed something in one form or another), but currently we have 5 team members (working on getting a 6th as well). Me, kaiser, google, sabatui, zoombie.