Let me assure you that it is not treated as a worse category product. Bear in mind that there is more to do for Cinema 4D, as the Max version has had many more years of development so has had much more time to mature (and hey, Corona 1 cost the same as Corona 4 there too, so it's not like they had "reduced pricing" early on either).
Also when implementing for C4D there are extra things that had to be tackled that Max never needed. Both development teams are separate, so there's no way it can be treated as "worse" (as in, moving devs to work on Max rather than C4D - doesn't happen). So there are a larger list of issues to be tackled for C4D than Max, including when things pop up such as R21 needing a lot of work to integrate with and backporting that to Corona 4 (which of course does take developers on the C4D team away from working on new features or other fixes - but we follow what the community is asking for the most).