If anything, TMP was the movie to dumb down treknology big time. Suddenly, robust small spacecraft that had looked like something Flash Gordon or Dan Dare would be comfortable with (the TOS shuttle) were back to looking like fragile NASA hardware (the workbees and their container trains). Docking maneuvers took aeons, compared with the swift shuttle launch and recovery procedures of TOS. Sturdy space stations like K-7 were "succeeded" by 20th-century-realistic scaffolding. Getting out of the ship suddenly required docking ports and airlocks, with dedicated operating crew operating dedicated control consoles for said. And transporter rooms went from utilitarian staging areas with lots of vanity covering to techno-temples with exposed machinery and a glass booth to protect the operator.
I'm surprised the movie didn't insist on having the phasers spit out spent cartridges...
As for Klaa in STVI, a quick comparison:
ST V forehead here
ST VI forehead here only...
Any ideas on backstage pictures where the latter could actually be seen?