An awful lot of apps use a map, and a static map in many cases isn't going to be enough. Likewise many apps will want to display video. Looks like they also have an issue open for webview support, which could be a problem too:
Looks like you could do the same for any view, so it's more that you can't have a subview which is a map or video etc, which isn't such a bad limitation (not ideal, but at least it's not impossible).
(disclaimer: I work on Flutter.) Hi, thanks for the feedback! Would you be willing to "thumbs up" this issue? https://github.com/flutter/flutter/issues/73 It helps us when triaging. Thank you!