Were any of them forced into abject homelessness after Star Trek? No?
Well, they trained as actors and ended up eternally typecast in a show
on endless repeat throughout the 70s, 80s and 90s, but which paid them residuals only on the first two repeats. As far as casting agents were concerned, they were "in work". They started doing conventions on weekends for survival rather than winning film, TV and stage roles. And they were being asked, weekend after weekend, "What was it like to work with William Shatner?"
If they chose to
only tell rosy stories - and they didn't really get into the nasty stuff until
everyone started writing their autobiographies, anyway - the convention audiences are gonna get bored. So silly, fluffy stories about Shatner deliberately crossing his eyes (to either make everyone laugh on set,
or, to ruin the closeups of his colleagues, depending on who's listening to the anecdotes and reporting them in fanzines and the press) can end up sounding nasty.
You know, I've heard
all of the main TOS actors telling ST anecdotes on stage, and many over them in casual situations, and the only one I felt Shatner bitterness from was James Doohan. Takei's more highly-publicised, recent attacks have taken a different tone, sure, but in the 70s and 80s his Shatner stories seemed to be told with affection. They were delivered with humour, not malice, and were confirmed by appearances I witnessed by Grace Lee Whitney and Yvonne Craig. Even Nichelle Nichols
"But you haven't asked me why we all hated you..." jibe to Shatner, when he was interviewing them all for "Star Trek Memories", would have been delivered with her trademarked wicked/affectionate smirk.
The media is as much to blame for the idea that the supporting cast of ST dump on Shatner all the time. Imagine if, every time someone shoved a microphone at them and asked them to tell some Shatner stories, they said, "No comment". The media and the fans would interpret
that as hatred, too.