I have to admit that I always found this a little jarring. I get why they did it but the player basically arrived in a continent that's already been tamed.
In the long run, having this amount of infrastructure does age Northrend better. Sitting in a perpetual state of being a new frontier would be jarring as well. But for a fresh expansion it would have been more fun if they phased it. It was the first expansion that introduced phasing. Mists of Pandaria did this much better and Warlord of Draenor pretty much perfected the art of staging outposts in a new territory.
And of course finally Legion took a dump on it all by simply yeeting Dalaran into the Broken Isles.
THis is why all Blizzard needs to do is spruce up the entrance of Gnomeregan a bit and add a tunnel that runs into a loading screen towards the Mechagon. It's not much gameplay content, pretty much a gimmick, but it would be the keystone on the Gnomish lore.