Now you know me.
Incidentally, I spend an awful lot of my year traveling in places where my phone wouldn't get any signal, were I to switch it on. I think this app would work a lot better for somebody backpacking around Europe than banana boating down the Amazon.
The former may be the exact people the makers are targeting. For instance, my parents usually go on 'package tours' where a travel company takes them around in a group; usually its to Europe, AU etc.
On another level, it's even useful for finding the parts of a city you've never seen before. I've lived in Los Angeles my whole life, and have begun to find it very boring, but perhaps if I were to unlock parts of the city that I didn't realize I'd never been to before, I could make some interesting new discoveries and keep myself entertained without even having to travel!
Not all travel has to be to wilderness, there's just as much enjoyment to be had in visiting regular places, not just middle if nowhere kind of places. They might be boring to you, but that's a very narrow kind of thinking to assume that of others.
And unless you're spelunking, there's a very good chance that GPS is available. It's designed for the military, so reliability and accessibility are important. There are very few places on the earth that cannot see enough satellites to get a decent fix.
Not all developed countries are boring! It's just as much of a jungle in NYC as it is in any South American rain forest.