Khoi Vinh makes some good points about using an iPad for design work. Among his list of suggestions, I'd point out better clipboard support on iOS:
Robust clipboard. The Mac’s clipboard is still relatively simple—it holds one thing at a time and allows you to paste it in any app that supports its current contents—but iOS’s clipboard isn’t even as capable as that. It would be a boon in itself to have more pervasive support for that simple level of copy and paste throughout the app ecosystem, but I would argue that iOS’s far more constrained interaction model should sport an even more advanced clipboard than the Mac’s. You should be able to save multiple clipboard items of multiple media types; each app that supports the clipboard should allow you to paste the most recently copied compatible item. That would significantly reduce the friction inherent on iOS in pulling together content from multiple sources.
Requests for better clipboard management on iOS go back a long way. Even trivial tasks such as copying rich text from one app and pasting into another one can be problematic on iOS (for "fun", try to build workflows to paste rich text in iOS 9's Notes. I'll wait.). There are excellent solutions for third-party clipboard management (Clips and Copied – I use the latter now), but it should be native to the OS. There's still plenty of low-hanging fruit for Apple to pick on the iPad.