[ilikepi]

The benefit is to eliminate the disadvantages and complexity (however opaque) of running NAT.

I don't think anyone is suggesting that all devices be reachable by default. It's entirely reasonable and prudent to have a firewall between my home network and the world, but NAT is not strictly required for this.

[tjoff]

That is a benefit, true. However I don't feel that it is comparable to the drawbacks.

I'm not suggesting that anyone suggest devices being reachable. Them having a unique identifier is bad enough.