Did they do a nerf to WT3 that I don't know about?

When I turned 50, I did the capstone and kind of hit a brick wall transitioning in. I grinded a few levels and didn't do very much gear optimization.

3 levels later, and just getting a couple of aspects my build needs, its a completely different game.

I'm sure I'm going to hit another wall at some point, but is this the normal experience?

Well the aspects were probably the problem. As you continue to upgrade them you'll only get better.