It's deeper than "OpenGL is hard." Right out of the gate, you are hit with the one-two punch of different texture compression formats being supported on different devices combined with a maximum APK size on Google's store. The only standard Android texture format with compression is ETC which doesn't support alpha. So right at square one, if you want to use compressed textures for maximum performance and resolution, you have to release 3 separate APK's with a different supports-OpenGL-texture tag in each manifest. One for DXT, one for PVRTC, and one for ATC. Or dynamically download megabytes of textures after detecting which GPU you are running on.
That's a sharp contrast with iOS's unified, simple developer story: all PVRTC without any maximum app size.
That's not iOS's story, it's Imagination Technologies' story. The story from Apple will change the moment they ship a device on someone else's GPU. If this is something you expect to rely on, you're in the position of someone writing Altivec code in 2005.
But yes: texture compression formats and hardware support are a terrible, terrible mess. Happily I believe the early patents on S3TC are set to expire soon.
That's a sharp contrast with iOS's unified, simple developer story: all PVRTC without any maximum app size.