The tablet support was around for a small period of time last year, but shifting to it suddenly caused problems for smaller screened apps, or apps running on smaller screens . I've heard a rumour it's coming back but getting the new MITserver going is their main priority at the moment..
As for the why not just learn Java, why not learn astrophysics and build a universe, I'm not being cheeky, Java is faster etc and yes has the full sdk but if you want to be able to make a simple app, or demonstrate an idea to someone without having to be a programmer, this is the tool. Plus it helps you learn a bit about programming basics. However appinventor has gone through some significant changes in the 2.5 years Ive been lucky enough to use it for. The team are amazing and the community here offer guidance and forum support that is quite frankly too good to be free.
Why can't you make a simple user interface ? Have you checked out all the resource sites ?
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