I've long thought that the display-half of the smallest MBP would make for a good tablet size, and that the original iPad was smaller than it needed to be – weight being the primary concern.
This could allow for a full-size keyboard in portrait mode (The format for websites and many documents, after all – unnecessarily widescreen monitors are a pet hate of mine, kinda, anyway.) in addition to a finally sensible display-area:keyboard ratio. Modifier keys only presently useable on bluetooth keyboards could even feature, furthering productivity.
More component space is a given.
To those talking about comfortable use: In enterprise or education, where a decent amount of content production takes place, there are desks. Use in motion as if it were a phone is clearly not going to be the most efficient, but I imagine that the weight would be low enough to allow it to be 'cradled' in one arm.
If this product really is the first of a new category, i.e. Pro product it may be that the most commonly used apps are exclusives which demand increased resolution, real estate and power compared to their lighter, present iOS counterparts.
An Office app that can lets you switch between multiple documents of the same type would be welcome.. as would for many a more robust in-field Photoshop app or similar.