The key is the trivial deployment. If a user wants a little app, and he has no server and no hosting provider, and he doesn't know how to install software or configure a shared hosting account anyway, then he is likely to just give up before he even gets started. This at least gives him a chance.
There are a lot of business people that have become programmers by building increasingly sophisticated Excel spreadsheets or Access databases. This type of "casual" programming is becoming increasingly common.
That said, I think that DabbleDB might have a more successful approach--data first, instead of code first. That approach made MS Access very successful. Casual programmers care a lot about their data, but code is just a nuisance that is tolerated to get the data to "work." People want assurance that their data is always there, even when the code is broken. In MS Access it is trivial to back up your database and view/hand-edit your data.
There are a lot of business people that have become programmers by building increasingly sophisticated Excel spreadsheets or Access databases. This type of "casual" programming is becoming increasingly common.
That said, I think that DabbleDB might have a more successful approach--data first, instead of code first. That approach made MS Access very successful. Casual programmers care a lot about their data, but code is just a nuisance that is tolerated to get the data to "work." People want assurance that their data is always there, even when the code is broken. In MS Access it is trivial to back up your database and view/hand-edit your data.