I've always wondered what precisely about Shatner caused such a deep grudge in cast members like George Takei, James Doohan and Nichelle Nichols. That at least gives a glimpse of what's at the core of it.
I recall when Star Trek V was announced, and a Trek-enthusiast friend told me it would be directed by Shatner instead of Nimoy as the previous 2 were, and added contemptuously: "It'll probably be a two-hour close-up of him."
I always loved Shatner as Kirk and in other roles. But I can see as a supporting actor who was struggling for just a few lines of visibility, how Shatner squeezing you out to just more emphasize his already starring role, could be both offputting and threatening.
