SH is a "minimalist" when it comes to his profession...that's his style.....he would be the first to tell you that...he makes very small and subtle improvements(unlike Steven Wilson and Elliot Scheiner)..which is fine when the source material is good...and in the case of the Doors that's exactly what he had to work with...
But that's the difference between a mastering engineer and a mixing engineer.
Good mastering engineers should make subtle improvements to an already great mix. The worst the mix is, however, the more latitude they have to make more dramatic adjustments if possible. After all, you know what they say about polishing feces…