I'm usually more frustrated by the restrictions imposed by apps. Can't copy-paste, can't adjust text size, can't export the list of stories read or archive them, can't apply my own filters, can't use it on my desktop, etc.
For example, I can't use Circa, due to [1]. With email, this kind of stupid restrictions just don't exist. Though I agree that email is not the best platform for this activity: I prefer RSS/Atom.
Not to mention all the one-click-for-more, filter-by-category, etc. features that come with a native app.
It just doesn't make sense.