[fauigerzigerk]

Functionality is often largely independent of platform specific features. Spending limited resources on re-implementing stuff five times over can result in a worse experience for users than focusing on a single high quality cross-platform solution that is easy to distribute and keep up-to-date.

It completely depends on the specifics of the app. Some apps benefit from tight device integration. For others it's a waste of resources that could be spent on features.