I agree with this - Marvel doesn't have a defined look. Star Wars locations, for the most part, all exist with a few similar types of aesthetic. Something can "look like Star Wars". Marvel lacks this.
I would also extend with these two ideas:
1) Until Galaxy's Edge, Star Wars got pretty much the same treatment. Granted it wasn't very long, but their representation in the parks was limited like Marvel is now.
2) Obviously, Disney cannot/would not do SW:GE expansion simultaneously with another major land expansion. It is possible they are completing SW:GE and trying to figure out a contractual way to do their full-on Marvel expansion down the road, without the current limitations on their Imagineers.