This is only something they ALWAYS do once an expansion is over. They want people in the new areas and, yes, they want people to feel like they’re not behind if they aren’t going to old areas. You have to keep in mind, there are players out there now who don’t even have a garrison, for example. (A couple of my much newer characters don’t!) They don’t want people feeling left behind.
I’m not sure why this shocked you. What shocked ME was they waited this long to nerf the gold income from it. I was expecting the gold to be gone with the PRE-PATCH. When it wasn’t, I was surprised and thought for certain it would be gone with the expansion launch. When it still wasn’t, I was frankly shocked. 
It was nice, however. Before they took it out, from expansion launch to it’s removal, I made a last about 50-55k gold off it with my extended stable of alts.