I think the GP's are pretty good the way they are (assuming the already announced changes to Healers and Great Healers). It makes sense for settled GP's to give points towards more of the same. If you don't want them, but *do* want to settle them (I think only a problem for Healers and Merchants... Prophets and Sages are pretty useful to make more of, I'm never tempted to settle Engineers anymore, and frankly I never get any Bards in the first place), then you either have to settle them in a different city or try to offest their contribution.
Ironically, I used to consider Engineers one of the more useful to settle (if I didn't have a wonder that I really needed built right awy), but since there has been an addition of like 6 good buildings that only Great Engineers can build, that's subsided. Anyways, those buildings have also made GE's more essential late game, so again if you *do* settle one, the bonus GPP's are pretty much an unmitigated bonus.
Also I agree that some of the analysis of Healers and Great Healers is ignoring that the average specialist costs you 2
+ 2
. So while the Healer basically offsets himself and gives one
, the Sage just turns 2
+ 2
into 3
(ignoring the GPP's from both). I think the original changes to Healers and Great Healers is probably enough.