And, if you need to send multiple docs in an email, this can be achieved with Documents to Go.
Attachments are a real weakness in Mail, especially if Apple wants business users to take the iOS seriously. The need to cut and paste into another program a reply with attachments, or start in the other program to begin with to send a new email is counter-intuitive and too many steps, especially if you're trying to do this sort of thing while mobile.
Apple needs to spend more time working on its core iOS business products (like Mail and Pages) if it really wants to be seriously considered by those users and less time on ways to get us to use their App Store (like Newsstand). Otherwise, users will use other devices or 3rd Party Apps will take over from their lapses.