I think part of the problem is in most of the video footage we've seen, the audio sucks. If you listen closely you can hear some quotes. Especially when they enter the stage.
The version of Jak and Cole that they released was unfinished. not even all of the animations have been put in. When Daxter said his little thing when they were first revealed his face stayed perfectly still. There will definitely be dialogue during the fights dont sweat it.
I noticed the same exact thing, although Cole at least puts on a smile at the beginning of the battle. Jak just, stares. Even in his winning pose. It's creeping me out man.
By the way, just call me Count for short.