Hmmm, this is an interesting point, though I have a question pertaining to it: Why is it that traveling cannot be part of the fun of the event. Let me pull an example from the game itself.
Have you done the Castrum Novum mission? (Off topic, but if not, I highly recommend it, hours of fun *cough* anyway) This is an example where classically the "event" would be the 15-30ish minutes long fight in the back of the outpost. However, the actual time it takes to do the event, traveling included is probably closer to 1-1.5hours due to walking all the way from the gate to the instance. This extra hour is merely "travel time" between the teleport and the event itself, and yet, many people I have talked to find it just as compelling as the instance itself.
"Slow" travel has somehow become a dirty thing, something boring to slog through to get to your actual content. Changing topics to your last sentence, you'll notice I never mentioned "immersion" in my first post. This is because I tend to agree with you. Immersion is a bing word that doesn't mean anything important and should have little to do with actual design. At the same time, I believe "travel time" is a critically important component of an event and does not in any way need to take away from the event itself. I would, in fact, contend that it is itself part of the event.