It ain't no big thing but it has bugged me from day one. You colonization a planed that gets 10-50% bonus to say research; that's less than one first (@10%) tier i building and tier2 with aAd buffs (@50%). Same with most colonization bonuses. It kinda takes away any real incentive to keep the planet specialized in the given bonus area. Yes it is better than nothing but usually not by much. Just spit balling here but 50-100% might be better. It would be ~the equivalent a +1 tile if you stay with the plants "intended" focus.