It's not an issue for a number of reasons:
1) IPv6 makes it *possible* to give every device its own address *at a reasonable cost*. There is no reason you can't do this with IPv4 too, it's just prohibitively expensive and so not commonly done. And there is also nothing actually forcing you to do this with IPv6 - you simply have the option to. People configure IPv6 without NAT not because IPv6 doesn't support NAT, but because they explicitly want to get away from NAT because it's simply a bad thing. You're complaining that a new car doesn't come with a roll of duct tape to hold the doors on, when it has doors that stay closed on their own.
2) NAT doesn't provide firewalling, NAT requires a stateful firewall but a stateful firewall does not require NAT.
3) All of the IPv6 capable home routers i'm aware of do not allow unsolicited inbound connections by default.
4) Protocols like UPNP exist which allow devices inside the network to open arbitrary ports through the firewall - this works on IPv4 too, and is worse on IPv4 (see 5)
5) IPv6 address space is vast, assuming you do leave something open either intentionally or unwittingly (see 4) the chances of it being discovered by an attacker are extremely small. Attackers routinely scan the entire IPv4 address space so anything left open will be found very quickly and exploited if vulnerable, this simply won't happen on IPv6 because it's not practical to do.
6) Modern windows devices (and mobile devices, and other operating systems) simply don't have as many vulnerable network listening services by default as they used to. Windows for instance now comes with a software firewall which blocks unsolicited connections by default. It's not like the early days when MSRPC and SMB were exposed by default.
7) You are putting your device at risk of attack every time you connect to a public wifi network (users on the same network will be able to connect to any services you leave open), but (see: 6) modern software is simply a lot less vulnerable to this kind of attack than it was. Public wifi is everywhere now, and used by millions of people every day.
The fact that phone networks are more likely to be using IPv6 is because phone networks are newer and have many more users, so they don't have enough IPv4 addresses to provide one to every potential user. Mobile services almost always put you behind CGNAT which causes all manner of problems and costs the operators a fortune to run.
This kind of ignorance is very damaging to progress.