I'm almost certain the mob placement was tentative in the Beta (especially in higher level areas). Actually I am 100% positive, and I'm sure they'll continue to change it even after release.
As for what you called "Copy paste terrain" are you referring to the blatant use of tiling on the textures? There's a few places where this is really obvious, as a game designer myself, and a LS of real life friends, most of whom are game artists or designers, we have fun pointing things like this out.
There are a ton of spots in Ul'Dah where the brick tiling is pretty bad because there's nothing to break it up. Another place that comes to mind is, across the big pond in front of the Adventurer's Guild in Gridannia, the cliff has really bad tiling.
If you were talking about the actual terrain meshes themselves being reused, I didn't find it too noticeable. But both of these things are simply byproducts of working on such a large project, and such a large world. Lots of times you don't even notice how much content is being reused, but occasionally the world designers fudge a job and it becomes obvious. Hopefully they have polish passes even after the retail release on areas, but I highly doubt it, considering it would make the patches huge, depending on how they deal with areas in their file structure.