There seems to be a widespread sentiment in pretty much all western culture to see money as dirty. I wonder if it somehow comes from old Christian laws against credit. It took me a bit to shake that irrational sentiment. Money is choice and freedom and no dirtier than objects one might gift it exchange.
Money is not dirty, but money corrupts everything it touches [1]. Doesn't matter if that's healthcare, internet, art or computer games, having money as a part of equation twists incentives and changes the overall picture into a darker one. It is (obviously) necessary for survival, and so it's not bad per se, but there's nothing wrong with longing for money-less interaction.
[1] To be fair, my belief in this may also come from the Christian background of Europe.
I believe the issue is that children are involved. If Roblox re-oriented itself to become an education platform where children can explore and learn different things virtually... that would be a win/win. e.g., Roblox could say, if you create a mini game that fulfills this lesson plan about chocolate [1], then your minigame can be published in the Educational section of the platform. Parents could then let their children participate in the Educational games only. I would for one would gladly donate/pay for such a service.
BTW the lesson plan for chocolate asks students to design a new chocolate bar. Choose the ingredients and design a wrapper. The students/players can then vote on their favorite design etc.