I've heard the "webstart is broke, don't fix it, move on" song before from a number of people. What I haven't heard is a credible solution to solving the very real problem of keeping an app up-to-date in a corporate setting. For the most part, I agree that if you're in the business of selling commercial software, selling and distributing through an app store probably makes sense for you. Although I wouldn't relish having to build on all of those platforms.
However, posting proprietary apps to external OS-specific app stores doesn't really work for anyone in a corporate setting. Neither does making a user re-install an application every time you post a bug fix. In addition, many corporations limit the privileges they give users. Cheers, Mark