A lot of the things Wesley said in the old (New Line) chat rooms were along the lines of...
He was not allowed the same creative input he had during Blade 1 & 2. (And it shows)
The original script theme he signed on for was changed behind his back. He felt he was being used as the fall guy to start a Nightstalkers spin off franchise (In which he was). The original story was supposed to take place years later after Blade 2, with the humans already being enslaved by the vampires. No Dracula. It was in their best interest to listen to Wesley because the Nightstalker movie got scrapped and the Blade tv show flopped without him.
He had become friends with Goyer and starred in his film Zig Zag because he believed they had a mutual understanding about what they wanted to do for the next Blade film. The studio didn't want Goyer to direct Blade Trinity because he did not have directing experience at the time. Wesley helped get Zig Zag off the ground to help Goyer prove to the studio that he could handle himself in the director's chair. When Blade Trinity wasn't going as planned, Wesley felt betrayed.
During open question, Wesley warned fans that he would not be doing any interviews to promote the film. (That's when we knew things were really getting bad). He had said something like "I promote movies that I'm in, and unfortunately I'm not in Blade Trinity". He pulled out of all public appearances, comic conventions, and promotions. I chuckle now looking back because when you watch the film it's almost like Blade is a secondary character.
Wesley is a method actor. Once tension arouse, suddenly Wesley was "difficult" to work with, even though he was method acting in the first two films. Although yes, once things were getting rocky he only showed up to do the bare minimum requirements. There was also an incident where they claimed they "smelt" marijuana coming from his trailer.
The scene where Wesley talks down on the Nightstalkers calling them "rookies", is actually off script and how he really felt about the film. He basically badmouthed them in that scene and returned back to his trailer, refusing to do a retake of the actual lines. The scene where Blade neglects to unchain Hannibal King, and heads directly after Dracula is also off script. The scene where Wesley goes back for his sword and says "forgot my sword" is also off script. Yet these are some of the best scenes in the film. Wesley obviously knew how to play the character, yet everyone continued to ignore his input.
I'm not defending Wesley's behavior or how he dealt with the situation. I just wanted to explain the REASONS behind it. These are just conversations that Wesley had with the fans. His side of the story. It's all he said she said from both sides really. Just wanted to share.
If you listen to the audio commentaries on Blade 1 & 2 its like him and Goyer are the best of friends. Goyer has nothing but positive words to say. Then play Trinity's... and it's like Goyer is talking about a totally different person. Always downing Wesley, pointing out every flaw, and every shot where "that's not Wesley that's his stunt double". 8 year friendship out the window.