I actually agree with your assessment that AppJet seems limited as compared to renting your own server or part of a server, for general development. The original idea of AppJet was for it to be a place for simple 1-page apps -- apps where the effort required to set up hosting greatly exceeded the effort to code the app.
A natural extension of this was to write a guide to teach people how to program. AppJet is still the only place I know of where you can learn to program and actually build an app that you can share with friends via a URL, all without downloading any software or configuring a development environment.
Now we are working on addressing all the limitations of AppJet as compared to having your own server, and therefore make it a platform that you'd use for more "serious" apps, not just 1-pagers. Hopefully when we release the next version, you'll give us another look and decide we compare favorably to the alternatives for general development.
A natural extension of this was to write a guide to teach people how to program. AppJet is still the only place I know of where you can learn to program and actually build an app that you can share with friends via a URL, all without downloading any software or configuring a development environment.
Now we are working on addressing all the limitations of AppJet as compared to having your own server, and therefore make it a platform that you'd use for more "serious" apps, not just 1-pagers. Hopefully when we release the next version, you'll give us another look and decide we compare favorably to the alternatives for general development.