I've run an IRC bouncer and SSH reverse tunnels over Tor for years. Not for the privacy but just for the ease of use. Also it reduces concerns with maintaining up to date linux hosting. While the risk of my .onion being discovered through the cat-and-mouse game that is de-anonymizing .onion's may permit some 3 letter agency to discover and root my host I at least reduce the attack service drastically by completely removing internet script kiddies from the threat model. So their is a security benefit in addition to the NAT transversal. The NAT transversal really makes a different and very easy reverse workflow possible. With some simple haggling with scripts and SSH you can reverse almost anything that is low bandwidth. I totally agree there is something to the ease of use provided that services have not fully explored yet.

And since most single-peer to home services never require an exit node bandwidth is never an issue. File transfer, remote mail, even a reverse tunnel to use a home IP as your exit node, all work with little to no bandwidth constraints. I really believe there are services to be built on this ease of use. Things that utilise these features without requiring one understand SSH reverse tunnels and the likes.

Finally, somehow I think the more services built on such a model the better we will understand how to fix some of the major flaws of the internet as a whole. Namely discrimination based on GeoIP comes to mind. If the internet were built in this manner instead of addressing a service I could have it address me through my own .onion reverse I think location discrimination would become a much more complex task. GeoIP is becoming much more fundamental. as the xkeyscorerules100.txt shows GeoIP is no longer just something used by media companies to prevent someone watching TV out of country and is today used to determine citizenship and basic civil liberties.