The problem is that they didn't replace them with smaller regular trees, they replaced them with a couple shrubs that won't get much bigger/taller than they are now.
A few years ago (I know it was before the Hub redo), in Town Square they had to replace the original trees that were there from Day 1, because they'd outgrown the available soil. The new trees made it look a little barren at first, but they've since matured and filled in nicely. The current Hub is still barren.
While I understand why they removed the curb around the Hub, and agree that in the long run it's probably best, I'll admit that it looks rather odd without the curbs being there.
As for the planters, they need to bring back some kind of smaller trees that can be allowed to grow and mature.
-Rob