But if it is ever to be taken seriously as a game of skill I don't see how deliberately trying to verbally put off your opponents can be part of it.
There's trash talking as a part of a bunch of other skill games. Boxing would be a good example - they even organise an official pre-fight rubdown contest under the pretense of weighing the guys.
And you should see those Chess guys talk trash !

(Ok, the last bit was a lie - but still
edit: ok - there are a bunch of these already - sorry. But I'd just like to add that speech play is a great thing - if I wanted to sit silently playing hands I'd stay home and play online. Seriously - if someone can talk you into calling then you might want to revisit your decision making process. And there's plenty of times when "How silly are you going to feel, saying that you put all your chips in with that hand ?" has, in my opinion, swayed the decision.