My own little theory is that there was, quite simply, no good shuttle to be picked up by NASA.
It was all a matter of internal / external tank Vs booster.
Internal tankage was too hard, yet external tankage bastardized the shuttle. Then the booster: the Saturn S-IC was tempting, but how do you recover it ?
IMHO the best they could hope for was more or less the orbiter / external tank as we know it, with a ballistic recoverable pressure-fed falling into the ocean. Unlike the S-IC, a pressure-fed booster can withstand a brutal fall into the ocean.
Another issue is wether the SSME light on the pad or in flight. Massive butterflies there (Ares 1 !)