You get substandard desktop applications that tend to frustrate people who are deeply immersed in any one ecosystem and expect native applications to have deep integration with each platform and comply with each platform’s design sensibilities.
But history shows that applications written against cross-platform toolkits have done just fine, as have applications that completely embraced “going native” on particular platforms.
I’m left with the thought that either strategy works if you go “all in,” the mistakes come from:
1. Going cross-platform but then doing ridiculous back-flips to try to make the app feel really, really native. Just take what the platform gives you, and accept that you’re giving people a web-like experience that happens to have some native affordances. Learn to live with the few complaints from retro-grouches.
Or, 2. Going native, but skimping on deep integration and fully embracing the look and feel of each platform. This is one of those “penny-wise, pound-foolish’ strategies: You ship faster, but you lose the big benefits of a cross-platform tool, and you don’t satisfy the users that appreciate what a native app offers in look, feel, and integration.