Here is a idea, when you create a game, have a slider that adjusts expansion penalty!

Ok, so the thought was is at the start of every game, the galaxy size determines the expansion penalties on colonization.  

But what if you wanted to play a HUGE galaxy against 4 opponents?  It can't be done unless 80% of the galaxy remains uncolonized or somehow you manage to stay religious for the whole game.  (IE never NOT had a war make my empire eventually find itself voting military).  

Implement a way to adjust colony expansion impacts! Put a slider on there that lets you decide from extreme problems to zero effect.  It could be on a advanced tab in the galaxy generator.  

It should be pretty easy, because I think its just a modifier at the start that sets the same rules for everybody.  

The benifits of this idea are HUGE galaxy multiplayer games with only 2 people, forcing a game where you can't have but maybe 2-3 colonies and your choices play a huge strategic impact on your ability to play ect ect.  

I just think this seems like a no brainer, because the system as is, is good, but its very restrictive, you can't get really creative AI games going, or you can't have a conquest victory in a very large galaxy without half of your empire revolting.  It isn't that I don't like the penalty, I just believe that if you want to play outside of a normal game, you should be able too!  Multiplayer 4 player's on a 4 spiral'ed collosus galaxy at a lan party?  I may never do it, but it would be a great option to have!