I can well imagine what it is. Their target market definitely doesn't include me, but as usual I am in the overwhelming minority.
Here it is: http://www.ubuntu.com/devices/phone No java "With all-native core apps and no Java overhead, Ubuntu runs well on entry-level smartphones – yet it uses the same drivers as Android."
Java overhead? Is that really a problem on Android? Especially compared to the overhead of running a full X11 desktop stack on a smart phone? I have seen how Ubuntu 12.10 performs on recentish hardware. I will not make assumptions here, but my expectations are rather low.