Very good points about why web apps have quality issues.
Some of those issues are not necessarily inherent limitations of the technology. We don't have to use Javascript, that's just what the standard currently is. Flash was a possible answer, as is Silverlight, in delivering apps over the web through a browser. Flash Air (check me on that) was a way to run a Flash app in what looked like a native format. Chrome 1.0 had a mode that hides all browser controls in an attempt to mimic the form of a native app. Java was restrictive in allowed functionality, but people added access to the Windows task bar, to OpenGL, to all kinds of things via JNI. We can add all those extra features to a browser via plugins. So it's technically possible to do all the same things from a browser. It's just a lot harder to get all the people in the middle to agree on reasonable technologies and then implement them the same way.
The large amount of OSs argument is interesting. On the one hand, that means there will be a large amount of mobile OSs for which a native app must be developed. That's a challenge to developers in itself. On the other hand, varying compliance with standards and various performance in a browser is another challenge to developers looking to reach all OSs at once via a web app.
Java could be brought up again, because of their write-once-run-anywhere idea. They did very well at making sure all Java implementations were compliant. But they had to offer a subset of full native capability, a limitation which was partly worked around by linking to native interfaces in a non-WORA manner. It sounds like any attempt to write once and run on every platform and have the software be as pretty and fast and functional as possible is essentially doomed. There will be limitations to those attempts (UI that doesn't fit in, no integration with platform-specific features like address book or task bar or spotlight, no access to technologies that only exist on a subset of platforms). But you still have the trade-off with the need to write many native versions for competing platforms otherwise.
Some of those issues are not necessarily inherent limitations of the technology. We don't have to use Javascript, that's just what the standard currently is. Flash was a possible answer, as is Silverlight, in delivering apps over the web through a browser. Flash Air (check me on that) was a way to run a Flash app in what looked like a native format. Chrome 1.0 had a mode that hides all browser controls in an attempt to mimic the form of a native app. Java was restrictive in allowed functionality, but people added access to the Windows task bar, to OpenGL, to all kinds of things via JNI. We can add all those extra features to a browser via plugins. So it's technically possible to do all the same things from a browser. It's just a lot harder to get all the people in the middle to agree on reasonable technologies and then implement them the same way.
The large amount of OSs argument is interesting. On the one hand, that means there will be a large amount of mobile OSs for which a native app must be developed. That's a challenge to developers in itself. On the other hand, varying compliance with standards and various performance in a browser is another challenge to developers looking to reach all OSs at once via a web app.
Java could be brought up again, because of their write-once-run-anywhere idea. They did very well at making sure all Java implementations were compliant. But they had to offer a subset of full native capability, a limitation which was partly worked around by linking to native interfaces in a non-WORA manner. It sounds like any attempt to write once and run on every platform and have the software be as pretty and fast and functional as possible is essentially doomed. There will be limitations to those attempts (UI that doesn't fit in, no integration with platform-specific features like address book or task bar or spotlight, no access to technologies that only exist on a subset of platforms). But you still have the trade-off with the need to write many native versions for competing platforms otherwise.