Not a problem we would have if we had adopted new IPv6 years ago just because it's new. Connecting devices together when you don't own the router between is hard. It's harder when everything uses nat and stateful firewalls.
A product that relies on the user being able to change settings in their router is not a mass market product, so you don't see a lot of people build things like that. That's what I would want, that's what you might want, but most people want 'end to end' connectivity without having to mess with port forwarding, static addressing/DDNS update, or firewalling. Had those interfaces/problems been solved/simplified 10 years ago, we wouldn't have these conversations. But no one did, and we are here.
A product that relies on the user being able to change settings in their router is not a mass market product, so you don't see a lot of people build things like that. That's what I would want, that's what you might want, but most people want 'end to end' connectivity without having to mess with port forwarding, static addressing/DDNS update, or firewalling. Had those interfaces/problems been solved/simplified 10 years ago, we wouldn't have these conversations. But no one did, and we are here.