They were featured players, and some could be called back at anytime based on their contracts with the studio and their availability for the shows done at the studio during that time. Glorification came from the fans from the convention era which launched Gene Roddenberry to make a huge mistake bringing those actors back for the films.cult cross has a good point. In TOS, it seemed like half the bridge crew (Sulu, Uhura, Chekov) were glorified extras, even though they were supposed to be regular characters.
They lingered on for too long and I kept questioning why would these characters still be in the positions they were, and not get a promotion??? I mean, the historic events they've accomplished should've guarantee a commission and a promotion. Then I'd heard and read the slanderous things the featured players said about Shatner, as if they were cast members, gave me the belief the fans had ignited their egos, and gave them importance which in actuality wasn't there to begin with.
I still believe the Star Trek movies would've flowed better if those characters weren't there and given to a young actor who needed a break. I've wondered what they felt seeing Kirstie Alley, a new comer, getting such a huge role in The Wrath of Khan while they're just there grumbling about Bill? None of them ever thought if it wasn't for Bill, they wouldn't even be in the picture?
Roddenberry was no longer there or was a powerhouse for the studio, all Shatner had to say to Harve Bennett was, "Why do they need to be in the picture???" And the Motion Picture would had been their last appearance on screen. And I wish it was.