I agree with Jbrase that the VRA sort of creates a "separate but equal" political atmosphere by making it such that politicians from these districts are elected almost in a separate reality than everyone else. You do end up with a decent number of sub-par representatives in VRA districts who could never be elected anywhere else so it can be a bit like the US House minor leagues.
Whether this is an argument for or against the VRA depends largely on your point of view. Whether such representatives are "sub-par," or, merely different in kind from the run-of-the-mill politicians is a subjective question. If politicians elected from VRA districts merely differed from politicians elected elsewhere in melatonin then there really would be no point to the law.