Why would they? I guess its just down to NDK vs SDK. But I would think C++ would give me more options then Java, but then again I am unfamiliar with both so what do I know xD
More options.. not so much. The core of the android OS (like basically any OS) is coded in C / C++ because you need more interaction with the material, full control on memory (when and where it's allocate and when you free it) and precise timing for the hardware. Over that first abstraction layer Google decided to use Java for the most part because it's also a solid language, hides most part of that first layer and can run on pretty much any machine that supports the JVM.
Java is mostly mostly underestimated because of its simplicity in my opinion. There's a huge community and most people learn Java as their first language in school so it has a reputation of being an easy language and whatsoever. That's bullshit. The collections are great and way easier to manipulate than the C++ STL and garbage collection is just awesome too if you don't have to deal directly with memory. I might be a bit sold because I currently work for a company that uses mainly Java but as a high level software engineer I often prefer C# and Java over C++ because why re-invent the wheel and care about stuff you shouldn't when you don't have to.
Disclaimer: In no way am I saying C++ is not a good language. It's a superior language in many situations but just don't underestimate Java and why Google used it for Android.
