Actually, I spent an inordinate amount of time building exactly this in my head for most of the day following these photos. There are two major obstacles that I can think of:

1. Abuse. You will very likely get random dick pics and other terrible stuff sent to such a system. I suppose you could fight this by requiring registration with some id or something, but that's its own can of worms.
2. I don't know how common it is to have GPS enabled by default on people's cameras. On top of that, even though I have it enabled on my phone, 1 of the 3 photos taken that day had grossly inaccurate GPS attached to it, so now I'd be looking at building some sort of friendly UI to allow people to fix the GPS from their photos.

The server-side stuff is easy (at least for someone with my background) but the front-end is sufficiently complicated that I couldn't do a good job on my own.