Another possible factor is that Apple is made up of lots of different teams. It's possible that the Logic Pro X team wanted to provide upgrade pricing, but the

Another possible factor is that Apple is made up of lots of different teams. It's possible that the Logic Pro X team wanted to provide upgrade pricing, but the app store team (or higher-ups) did not want to permit this. Without any further information (which we're almost certainly not going to get) it's difficult to tell if this is the case.