Not to condone the way they've interpreted file input, but at the very very least - you can upload almost any image in the system by either saving it to camera roll, or taking a screenshot.

This is really a lowest-common-denominator for file transmission - for example, until recently my mom couldn't upload her photo on meetup.com due to this limitation (she uses only an iPad)... I figure Apple cares more about her needs than mine (saving specs.xls into a JIRA).

Any other file uploads (docs, etc) are likely better handled by an app or simply email.