The game is not "all about the colony rush". I know because that used to be my main strategy and now it will cripple you if you take it too far. I play with much fewer than recommended number of opponents so there is plenty of room to expand. Don't do it. It's a trap. Mostly because it eats up administrators.
The game is not "all about the colony rush" because there are dozens of other things to worry about. My main issue right now is figuring out which resources I will need a hundred turns later. On this point I am convinced that the AI knows a lot more than I do. So far.
The game is not "all about the colony rush" but the colony rush is still important, and I can get more than 11 planets in 50 turns if the map is any bit at all friendly. According to Brad, I must be, by nature, if not by game parameter, expansionist. Be warned.