I dont think the answer is as simple as that.
You have a valid point as far as your community goes.
how ever there are other equally valid points.
races with diverse gene pool are able to withstand adversisties better.
Then is the THeological point which our scripture teaches us that we are all children of one GOD.
So How to reconcile is to do both a bit of Sikhi and a bit of out marriages so as to keep the race dynamic.
This is only an opinion i guess deeper thinking could answer this question.