Repeatedly called by whom? Fans? The trailer for Star Trek VI? They were just another starship in the original series. 78 years later, Scotty was dissed by Geordi, Janeway offhandedly criticized Kirk's methods. Spock, though, did get some spotlight by Picard and was well respected as an ambassador.
Kirk was revered by his crew to the point where they feel their success chances doubled when he took over from Decker. But starfleet didn't seem to be in a great hurry to put him in the center seat since he had to talked the admiralty into it and they kept promoting him out of it.
They were all apparently doing whatever else when they did the training mission at the start of Star Trek II - then got the silent treatment after the Genesis affair. In fact, they seemed on the outs at that point: no new assignment for anyone but Scotty, the Enterprise decommissioned. Pretty low treatment for Space Legends.
Once they saved the world it was Kirk, more than anyone else, who got the glory. He got a new command and everyone got their old jobs back.
"I need Jim Kirk!"
"Oh, please," he responds with insincere modesty, dragging the rest along out of the kindness of his heart apparently.
Anything stated after the fact is not the responsibility of TOS or the first six films, but while they were doing films, the crew was the crew. "Oh my god, it's PAVEL CHEKOV!" said nobody ever. After that, fan films and ego stroking was all it was. Captain Uhura, President Chekov...come on...
What is this thing among fans that everyone has to be a captain? Or be in the command track? Maybe some of them aren't as career minded or want advancement like others. Promotions aren't all they're cracked up to be. Not everyone is suited for command - and if ALL of the OG cast are captain material, then Kirk, Picard and so on aren't all that special.
Anyways, by the time of Star Trek IV, they no doubt had their pick of assignments and apparently wanted to stay together until Sulu had enough of the BS.