First and foremost VRChat is not a game, it's has always been a social platform. It may have games in it, but people most of the time come to vrc to chat and chill, not just to play a game(s). Besides, the games that are in vrc are greatly overshadowed by the sheer amount of social worlds that people go to either privately or publicly. That's why you would see game instances with ~30 people have 10 or less in the game and the rest scattered about just chatting around corners or mirrors.

With that said, children under 18 or older should absolutely not have access to such a platform and socializing with so many different types of adults that could very well harm their developmental state. Having a stronger method of keeping them out is more preferable, than just letting more circumvent any simpler verification process, which also makes the experience worse for adults too anyways, because it would be essentially an unnecessary verification process that slows down the adults from entering and doesn't stop the childern from entering anyway.

When it comes to missing out too, there's nothing stopping you, your partner(s), or your friend(s) from starting a public/private instance and hanging out with you, as the verification blocking powers are in the hands of the user not vrc itself, and missing out on group events and NSFW avatars/worlds/events would just be something that people would have to deal with, because any exceptions would mean letting kids slip through the cracks.

I do like the alternative idea of a VRC+ paywall to an extent only because it ends up being that it would be biased towards people's finacial situations as well as the location of the individual too, because some countries have weaker money power to the USD, so it would be ultimately unfair for them. It would make things far harder for kids, but I wouldn't to exile an entire fanbase just because I had the finacial ability to do so.

I would go for more of a separation of "free user", "gifted user", and "VCR+ user". Free Users can have free open access to making public and private instances, but don't have the same access to all mechanics and instances accessable to Gifted Users and VRC+ Users. Gifted and VRC+ users can still hangout and join instances with Free users to hangout, but not the other way around, because it would ultimately be the layer of defense to keeping children of the adult spaces and showing favoritism to anyone in that's a free user would likely let kids slip through the measures.

Finally for the use and access of NSFW worlds/avatars/events, that would include matters that are adult explict (not just sexual) and that would require age verification of some sort of way. Not a paywall, because that would be too easy to break though, and if not by ID submission, than there needs to be alternatives that can prove someone is who they say they are and that they are indeed an adult to have access to the NSFW or "Age Verified" status.