However, OW is principally a marketing alliance, with a few benefits such as interlining of baggage and reciprocal use of lounges thrown in.

I agree with you, a one-stop shop for bookings would be more user friendly but if the OW timetable can't even provide reliable information for all of the carriers which are part of the alliance, there's very little hope for this...

I would imagine that members working from a position of dominance in their home territories (can't think of a single OW member exception here) would probably not take too kindly to the idea.