Here's an article from the May 1990 edition of the awesome magazine "Cinefantastique," where Walter Koenig spills the beans about the then-planned "Starfleet Academy" movie which could have been ST 6. Thankfully, it was never made, and we got to see our heroes one more time in a grand send-off, "The Undiscovered Country." If Walter's efforts to alert the fans (and the resulting backlash) factored at all into the studio's decision to scrap the idea, then we should be grateful to him.
Of course, Star Trek '09 was in essence the same idea; recasting the characters with younger actors, showing the Academy days, and even using Nimoy as an anchor; but enough years had passed that by then, we were ready to revisit the original show and were willing to accept new actors if it meant seeing the TOS crew in action again.
Bonus: Below, a silly article from the National Enquirer tabloid, published in September of 1983, that tries to use Star Trek to lend "credibility" to it.
"Uh, you should be gettin' back under the beam, Cap'n, unless ye want to lose the left side o' yer body, sir."