Supporting multiple densities does seem pretty standard. Google recommends it all over the Android developers site.
As Ninjadoodle says "The other bonus is that if you decide to update your apps in the future ( as resolutions get higher ) you can just upload higher resolution graphics with a (for example) — suffix and the engine will take care of the rest ( only use those graphics if the device is a very high definition TV or tablet )."
2 years ago we started developing at a 800,420 resolution for the Galaxy S, which seemed like a sensible mid-range device but is now becoming a dinosaur. In a few years time we'll need to overhaul all our apps and adjust all the pixel values if there isn't any screen density asset control. A nice simple system would really help future proof games, as retina screens and their Android equivalents get denser and denser.