Well, iOS 7 does support OpenGL 3.0 ES. If I'm starting now, why wouldn't I want to target it? By the time, I'm done with my first app, iOS 7 will be on over 80% of the iOS devices.
I checked and Android 4.3 supports 3.0. KitKat's low memory support should mean that even new cheaper phones will get Android 4.4 in the near future.
OpenGL 3.0 and OpengGL ES 3.0 are different APIs, with later based on a subset of OpenGL 2.x as same as OpenGL ES 2.0.
OpenGL 3.x seems like a dead end IMHO. I only follow the Kronos group antics as a spectator, so I might be completely wrong but it seems the 4.x is trying to clean the mess of 3.0 and not building over it. It could also be the reason the 3.x redbook did not get enough Amazon stars for your satisfaction.
I checked and Android 4.3 supports 3.0. KitKat's low memory support should mean that even new cheaper phones will get Android 4.4 in the near future.