I am going to tread carefully here, so do please read carefully...
We can only speculate on the exact reasons why the auto industry does not use Pro/E more for automotive styling. The fact remains that the Big 3 are heavily vested in their current positions and will remain so for a long time. There is little to zero incentive to switch.
Pro/E is a great tool, and I enjoyed working with it. A fair portion of that work was styling work for motorcycle OEM's and truck tier-1's. When used alone, PTC's product line is a
good surface modelling solution. Decent, but not truly great.
However, Pro/E has some shortcomings when it comes to interchange with other CAD and CAID programs used in automotive styling. This is a big problem if "A" surface data needs to be interchanged with other programs like Alias. I have had the opportunity to verify
firsthand that Pro/E alters
(corrupts?... that's a bit too strong) "A" surface data in such a way that makes it unsuitable for "A" surface design when data is exchanged with other applications.
For example, take a single trimmed B-surface generated in a CAID program like Alias. That surface has an underlying B-surface definition which is defined by a set of defining points and polynomial degrees in the "u" and "v" directions. When translated into UG (or even SolidWorks!) via STEP, IGES, or parasolid, the entire B-surface definition is included in the trimmed surface definition, not matter how small the trimmed portion is. When the surface is untrimmed, the full B-surface is revealed.
In Pro/E, the same surface is brought in with only enough of the B-surface definition to produce the trimmed portion of the imported trimmed surface. When the trimmed surface is untrimmed, only part of the original defining surface is there. What's more, Pro/E sometimes changes the polynomial degree of the B-surface (Alias often produces surfaces that are 5th degree in one direction). This is enough of an alteration to cause problems.
"When everyone is thinking alike, no one is thinking very much. --Eckhard Schwarz (1930--2004)