To be fair, the Trek 5 period seemed to be the height of his pomposity.
I had a personal anecdote at a "signing" at a car show around this time where Shatner looked at the line, freaked, and decided to just quickly shake people's hands and not sign. When I got to him, I had one line of interaction I wanted to have with him. I wanted to say I was looking forward to seeing him in Trek V. I opened my mouth and he stomped on it with a robotic line of asking me my name and saying "nice to meet you" and shaking me with his clammy hand. He just looked through me and didn't acknowledge that I was a real person. My experience of brief interactions with the other Trek stars at conventions was much more genuine.
I respect Shatner's abilities and his accomplishments in film and TV, but he is an obnoxious personality. He has been able to embrace that negative image and make it into schtick in his elderly years, but back in the day it was kind of a dirty little secret only known to those who came into contact with him while he otherwise tried to keep up his reputation as a larger than life action hero and role-model. Shatner didn't even do conventions, by a rule, in the 80s, and when he did the "Get a Life" skit on SNL it was kind of inaccurate considering how few he was dong. Now he does them all the time and is much more self-deprecating. He really has lightened up.