It's not that long, to be honest, and besides, I always talk to Arthas before running into the town. By the time we're buffed up, it's about halfway through and we could honestly wait a few seconds for lore reasons.

I hate when my ICC group complains about how the Deathbringer Saurfang encounter doesn't start until a minute or so after you talk to Saurfang himself. It's lore. If you don't want to hear it, don't die. Heaven forbid Blizzard wants to spice up their dungeons with some actual stories. And heaven forbid you have to wait an extra minute or two to be reminded what's going to go down soon.

Did they make Kael'thas' introductory speech any shorter? No.

*That* took long to listen. Go and try for yourselves :P

"Not that long"? We enter instance, get 15 min debuff, walk/mount and get the crates, talk to chromie thro 3 gossip screens, listen to lore, buff, listen more lore then he walks up and goes "everyone is ready" and then more lore against mal'ganis and citizens.
Now our 15min debuff has about 9 min left..
Then we do instance with timed and would have spare 5-7 min to spend.

I mean...sure its bearable but I don't understand why they haven't made it faster if they made ToC's similar length intros and HoRs intro skippable.

I would suggest using already done model for speeding up stratholme story:
http://www.youtube.com/watch?v=1_x5zDCjULw