Well, in class we do an even pace partly because it's easier for everyone to keep up that way, but it also helps to be able to concentrate on each move individually. Don't get me wrong, we haven't split up the counts that involve multiple techniques -- that woud be stupid -- but, especially because we often practice hyung when we're really tired from the rest of class up to that point, it's good to make sure you don't rush anything.
When it's my own count, or at a tournament, however, I most certainly do change the pacing to reflect those moves that flow together. In fact, that's part of tournament prep at my dojang, working on timing and pacing. A steady, even count all the way through would get a bit monotonous, and it would, as you said, blur the sense that this is a fight going on. Even so, I still get comments from judges (after my group has finished competing) that I should slow down more and make sure I'm not rushing (and these are not even all necessarily ITF judges).