The point you make about not having to scroll endlessly through your inbox to find 'that link' is moot when using Point a lot, because you'll be endlessly scrolling through the Point app. Also; what happens when the content changes and the quoted part is gone? Would be interesting for for example QA teams when you include Dropbox integration with a screenshot option.
If the content on the page changes, the quoted text will still show in the point chat box. Definitely useful to comment on Dropbox files/links.