the tech tree needs to be enhanced, that much is obvious. and luckily the devs have devoted themselves to said venture

but the question of the day is 'how'? I've seen some pretty good tech trees slapped on otherwise crappy games, making them fun. I've also seen 'feces'-ish tech trees that have ruined otherwise good games.
an example of the former; Earth 2160: crappy game setup, poorly balanced. big, well done tech tree. its fun regardless of its blunders (aliens are through-the-roof powerful, AIs ignore each other, poor optimization etc.) the tech tree is big, relatively cheap, but there are a LOT of technologies to learn, most games you go through with barely researching 1/4 of them (and you all know I'm a techno freak)

just to say, it can make or break a game.