Good questions, all of them. I think the answers are intertwined -- Tudor was affiliated with ABT for many years, as well as teaching at the Met and Julliard, but he made relatively few ballets, so the raw materials for an extensive retrospective are thinner than they might be for other choreographers. His contributions to the field were as much in the studio as they were on the stage. As beautiful as they are, his works never made up the majority backbone of a company rep as Balanchine and Ashton did.
I don't really think that his style is out-of-sync with contemporary tastes -- every time I've seen one of his works performed it seemed to make a big connection to the audience. And he's certainly on the wish list of most critics I know. I don't know about the financial aspect of things -- does anyone here have any information about the fees the estate charges for staging? (I know that kind of information is held pretty closely by most companies -- I'm not asking for deep secrets to be revealed)