Unfortunately customers tend to be happier with IPv6 turned off. There are lots of ways to misconfigure IPv6 and have it kinda work but slow and unusable. This is especially the case when you let users bring their own router.
Not really: Like was mentioned upthread, with CGNAT you end up fate sharing the reputation of a single v4 address with other customers, you get CAPTCHAs or just outright lack of service (eg instagram aggressively rate limits per IP). Not to mention worse service with apps that can use end-to-end connectivity when availabe, like video calls etc.
