Political discussions are usually polarised, and thus they start with pointless bickering and end with ranting flame-fests. People tend to enter the discussion knowing what they think, with little to no chance for changing their minds.
There are very many places where such discussions are welcome.
And most of those places suck. You have to wonder, can you design a discussion community framework in a way that enables more constructive discussions on these topics? Maybe something different than a straight threaded (or non-threaded) discussion forum? In the same manner that Stack Overflow tries to do it for programming and more general Q&A; not that I'm saying it'd work the same way as SO.
There are very many places where such discussions are welcome.