Since when, or relative to what?
Fans of large phones would point to the Galaxy Note series as introducing the phablet concept, which led to other Android manufacturers and eventually Apple following suit. Last year's longer screen, smaller bezel development also began in the Android world. To be honest I'd regard both of those as more significant than screen resolution.
Water resistance was first introduced into mainstream handsets by Sony (not Samsung, as I've read several ignorant tech blogs say in the last year, they came to it a whole release cycle later). Even Apple have now caught on to that one.
The openness of the Android system, which allows you to choose your own style of home screen UI (even down to replacing the launcher app), is something you don't find in other platforms. We don't even give it any thought, because it's been there from the start.