I would agree with you that there hasn't been a genuine hit since MOO 2. I would say, however, that one game, Distant Worlds: Universe, was a huge leap forward

I would agree with you that there hasn't been a genuine hit since MOO 2. I would say, however, that one game, Distant Worlds: Universe, was a huge leap forward in redefining what's possible in the 4x genre (i.e. deep and immersive gameplay in a real-time context). Most of the other 4x games since 1996 have been a variation on the gameplay mechanics of MOO 2. DW:U is the only 4x game that I would unequivocally say is as good as the original MOO2.