Developing apps to run on the browser still implies a lot of redundancy: you are forced to work with solutions that weren't created for interactive applications in the first place (HTTP, DOM), limited to one language designed by comitee (Javascript) and code reuse is minimal. Everything just feels hackish (at best) compared to native frameworks (e.g., Apple's Cocoa), and in the end it's hard to achieve good UX and compatibility.
I would rather see more people deploying native aplications with great UX backed by REST APIs than shoe-horning apps into browsers (which break the web).