Ironically, Apple did this in iOS 7, and this resulted in chat apps that could work even in the absence of a phone signal (e.g. FireChat, which now works on Android too). I think a big blocker from getting these to work on TVs is that TVs had non-standard OSes. With more TVs running Android, and Apple pushing SDKs for tvOS, I'll be surprised if these apps don't become more popular.
Every time there's a privacy issue with Facebook, HN is up in arms declaring Facebook dead but the truth of the matter is that most people just don't care.
Cost. Developing world people ... they maybe walk to market, maybe visit another village, they don't want to drop huge money on mobile data, which is stupid slow anyway and developers don't care about their use case. With local mesh it's fast enough that things work anyway.
Now, I'm no lawyer and I'm not interested in digging through Google's Android licensing fortress, but even if there are issues there, if there's a place in the world where a company can make the requisite API extensions happen and have them reach a mass-market product regardless of legality, it's China. That company will win the developing world low end smartphone segment, because cellular data simply doesn't exist in an affordable, user friendly and decent performance manner for most of the developing world's population.
It will bring a return of SMTP/UUCP-style store and forward. It may be the apple in the developing world's eye.
Closest thing out there right now seems to be http://developer.servalproject.org/dokuwiki/doku.php