If I had wanted a RWD performance car, I would have bought one. Over the years, I've driven various RWD cars, from performance to dogs. They shared one thing. They all sucked in the Michigan winter driving. "PosiTraction" (LSD) or not.
With the planned switch over to RWD for Pontiac - it appears as if this will be my last one.
I believe that we also have to look at the politics at that particular time in automotive history. IIRC FWD was considered the future for sedans at the time due to their better stability in rough weather conditions. I believe GM was being heavily criticized for not offering any large FWD sedans, when the japanese already offered FWD sedans. So I do believe that GM did good by offering FWD, but they seemed to have put "all their eggs in one basket" and made all their flagships FWD.