A trend I've been noticing increasingly over the expansions is that blizzard tends to use portals a lot more. Now call me crazy but I find that incredibly uncreative and lazy.
Let's not forget that wow is an mmo-rpg, and while fast travel might be available in most rpgs, atleast it requires you to go discover the location first.
In the Legion-prepatch quest where we go to Dalaran (Over Deadwind Pass) and witness Jaina's desertation of the Kirin Tor, we talk to Brann Bronzebeard, who has some urgent business in Ulduar. Instead of telling us (The player) to meet with him in Ulduar, he just happens to conveniently have a spare teleporter to the place.
Now I know that a lot of you have been to Northrend and Ulduar countless times in the past, you've probably seen every nook and cranny and you'd much rather have a teleport, but look at this from a new player's perspective. Chances are he's leveled up with a friend through dungeon spam, he probably hasn't even seen half, if even a third of the world Azeroth has to offer. For him or her, going on a journey to Ulduar could offer scenery they've never seen before, which adds to the rpg feeling of the game. With a teleporter they just go and do their business, then hearthstone back to Stormwind to afk. It's so unimaginative!