The mining is also usually a really polluting affair for the region, much more than the what power generation might suggest. And overall, in many countries there is a lot of subsidies going on for hidden costs, especially relating to the waste and initial construction. So it is not as cheap as a first look might suggest.
I'm not against it per se, it is better than fossil fuels, which simply is the more urgent matter, but it's never been the wonder technology it has been touted as ever since it first appeared.