Well then it's not just about software limitation. If we pretend there weren't any, would you still have made a sequel? If yes, then it's about money, and I would be okay with that if you had mentioned that was part of or fully the reason for making one; if not, we would still own the game and would get all future updates for free, and money would have nothing to do with it.
I'm not assuming that you're a bad person or anything like that, I'm just saying that if money was at least part of the reason for making a sequel and not just software limitations, then you should've mentioned it in addition to your other reasons.
Anyway, that's just my take. Good luck with the game!