The shatner haters will invade your post but I will give you the real reasons why Doohan hated Shatner..
1. He was jealous of Shatner. As you stated, Shatner took Doohan's lines. Well, TOO BAD, Jimmy. Shatner was the star of the show. And like Jack Lord, Tom Selleck, he had the right to trade lines...
2. Shatner often took credit for getting Jimmy the job. Shatner did suggest Jimmy for the job...and..wow..he got it!
3. Shatner revealed the fact that someone from the main cast, in a drunk state of mind, sexually harrased the woman who played Rand. Hmmmm..I wonder who that was.
Nichelle Nicholes? no...
Nimoy (Shatner's close friend...no...)
De'Kelley (class act..)
Koenig (wasn't there yet)
So that leaves either Shatner, who wrote the book, or Doohan.!! Now, in defence of Doohan, he is never named at the person who did it, nor am I..but you get the picture.
I have been to dozens of Trek conventions, starting in the late 70s. I have heard the lower rung actors bitch and bitch how hard it was to escape Trek's shadow. Well, Shatner did it, and so they are jealous hacks.
Okay ani-shats...time to spread more of your lies about the only Emmy winning actor who starred in Star Trek...WILLIAM SHATNER!!