I see no problem with this usecase. We need to implement a plugin selection dialog in any case, in which one could check the default plugin to handle a given payload. Then all we'd need to do is create a setting such that the results window is not displayed if not wanted (it provides the copy button, but with a default plugin has no other use).

Regarding opening the web-browser, there are two ways it can open - either in a new window, or in the same window; a settings dialog for the qrcode plugin could allow the user to select which of these happens.

I'll add these to my ToDo list