On the contrary, I think they've made it worse while washing their hands clean of it. Most, if not all, of the third-party developers don't verify licenses on their websites. They've effectively told these developers that they're on their own now. IPS likely felt like they weren't getting as much of a cut from marketplace sales anymore, so that's why they dropped it. I don't think it has anything to do with overhead on their site. That was such a ridiculous claim for them to make.
They've spent so much time being worried about pirating that they don't even realize they're driving themselves over a cliff with current development. They're neutering the commerce aspects of their platform, such as removing the integrated support system, and really made a mess of their UI with IPS5; looks like an amalgamation of Discourse and other various platforms. It's really an eyesore.