It would be terrific if, at some point, OmniFocus could (or could interface easily with a program that could) offer planning along the lines of David Seah's
Emergent Task Planners.
It would be an entirely new additional interface, so I imagine this is seen as beyond the scope of what OmniFocus is for. But since the time estimates and starred/flagged tasks are already being built in, perhaps it's not so farfetched an idea to have a space for dragging and dropping tasks into a daily or weekly planner.