universal colonization race advantage

[Nitram Draw]

It might not be to bad if you do as raynor suggests, make it so expensive that it is the only improvement you can choose and you must reduce other areas to get the necessary points.
The other alternative is to make it researchable at an extremely high cost.
It is great to have in the middle/end game when you have all the colonizing techs anyway. It makes life a little easier for something you have already.