I'm sure there has to be something I'm missing but I don't see the point of Mobile App Builder. I could see the benefit if it enabled you to execute code while disconnected from the internet and only re-connect when you click the save button.
Even though it doesn't create a mobile application per say, I find the Sitefinity Form Builder gives a much better mobile experience than the Mobile App Builder. The Form Builder UI controls look and function better than the Mobile App controls and the Sitefinity Website does not shut when the user loses an internet connection.
The biggest problem I see with Mobile App Builder is the applications shut down when losing an internet connection. For this reason alone I can not use it.