Not allowing inbound connections is arguably a feature for most users, not a bug.
I don't think that even given widespread IPv6 adoption, we'll ever go back to a model where residential or mobile internet connections will allow for public reachability by default.
Of course, NATs and firewalls are not the same thing (you just effectively happen to get the latter when deploying the former). But I firmly believe that the bulk of technologies that give us dynamic endpoint lookup and coordinated firewall traversal will outlive IPv4 and NAT.
As an anecdotal example, I used to have a mobile data plan that assigned a public IPv4 address to my phone, including inbound TCP/UDP reachability! That's neither good for battery life, nor for data consumption (on a metered plan). By contrast, my current one puts me behind a carrier grade NAT, but I have no problems whatsoever making peer to peer VoIP calls to friends behind the same type of NAT.
I don't think that even given widespread IPv6 adoption, we'll ever go back to a model where residential or mobile internet connections will allow for public reachability by default.
Of course, NATs and firewalls are not the same thing (you just effectively happen to get the latter when deploying the former). But I firmly believe that the bulk of technologies that give us dynamic endpoint lookup and coordinated firewall traversal will outlive IPv4 and NAT.
As an anecdotal example, I used to have a mobile data plan that assigned a public IPv4 address to my phone, including inbound TCP/UDP reachability! That's neither good for battery life, nor for data consumption (on a metered plan). By contrast, my current one puts me behind a carrier grade NAT, but I have no problems whatsoever making peer to peer VoIP calls to friends behind the same type of NAT.