Justus, it didn't happen like that.
It had a great opening weekend due to people being eager for ST on the big screen and because Paramount had spent a fortune marketing the beast. The buzz was huge; the first Happy Meal movie tie-ins were for TMP, for Christ's sake! But a great opening does not a successful movie make, and Paramount was disappointed with both the critical and box-office reception of the film. This is an established fact.
You have to remember that for all the money the film made, it still under-performed. And behind the scenes, there were countless rejected scripts, near-constant rewrites, the "Nimoy Situation," a failed television reboot, and too many time and effect overruns during the film's troubled production to list. Paramount had a literal crap-ton of cash they needed to make on this movie above and beyond production costs just to break even, let alone consider it a rousing success.
TWoK on the other hand was a comparative breeze to make. Smaller budget, no dragged out "development hell" period, highly engaged and disciplined director (no disrespect to Wise, who IMO did the best he could with what he was given), and very little spent on advertising... it pulled in less money overall, but it was so much less frustrating and so much less expensive to make, Paramount was delighted. They started ordering sequels almost immediately after its release.
Btw... I actually remember hearing that the next film was going to be about a "search for Spock" literally the afternoon I got home from seeing KHAAAAAN. I know the third film was greenlit almost immediately, which means I may have seen TWoK on a matinee the first or second day it was out. I've always wondered about that!
I'm not an expert on the subject but I thought it was fairly well known that ST TMP was a letdown both critically and at the box office. It was successful, however it underperformed to the studio's expectations. That is why Bradbury was booted, and the budget for TWOK was tightened.
Are we rewriting history here or wtf?
Yes. Justus is rewriting history.