Originally Posted by Neil S
It's holding the OS back that developers today can't rely on anything Google has added to Android since May 2010, when 2.2 came out.
You can use the Android Support Library
to include new OS features in an app that can run on older OSes. I'm still new to Android development and I haven't experimented with it yet.
I agree that Android presents some challenges due to the huge number of hardware configurations it can run on but that also increases your customer base. Android has a much larger market share than iOS and I'm betting it will continue to grow.