OP: The key to alot of the things you mention in your diagram is.... the interface was pretty clearly designed for 1) being seen on a TV screen across the room from you (rather than on a monitor 2 feet away), and 2) designed for use with a controller, and the specific ways a controller works. i.e, it's not designed around "quick movement of the cursor to position x/y, click" or "click and drag". It's designed around pushing a thumbstick up/down/left/right to make things happen.
The perk interface shows this clearly - pushing the stick L/R makes the whole list of skills spin right on by. A natural movement. Same for interacting with the specific perk trees - push the stick in various angles and amounts to maneuver among the stars. Meanwhile, WASD doesn't move between the points properly, and click-drag sends you in all sorts of directions.
Same for the vertical lists - push up/down to scroll the list through the central "highlighted" point (rather than go down to the bottom of the list and click on the category you want). Push right & left to switch columns. That's also why the lists start with the "top" in the middle of the column and not at the top of the screen - the "active" point for the list is at the middle height - the thumbstick scrolling action isn't moving the action point to an entry on the list, it's scrolling the list through the action point. (i.e, you don't move the highlight to what you want, you move what you want to the highlight)
And it seems like this should work fine with a controller - it's probably even good design. But it wasn't adjusted for use on a mouse+keyboard setup. So we're using an interface with I/O hardware it wasn't designed for. (kind of like turning a screw with a pair of pliers - yeah, you can do it. But it would work much better with a screwdriver.)
From what I've seen, the UI seems to be rather Apple inspired - lots of swishing and fancy stuff. It looks so nice and purdy, but it's bloody horrible to use. There's a lot to be said for practicality.
And aren't you also amazed at how many people love Apple products?? I say 25% of the market is pretty huge... for one type of phone! And customer satisfaction... Oh I bet you don't even want me to begin..!
The thing is..... it's not, really.
Or, at least, yeah, they got their inspiration by looking at Apple products ("oh, it's all so sleek and white!"), but didn't actually look closely enough. Apple interfaces tend to focus on being usable. Maybe not power-user "get under the hood"-ish, like a PC OS, but what is there is pretty much supremely functional.
The Skyrim interface just seems to have gone for "it's slick and white! ooooh, aaah!"
(edit: of course, Apple's screwing that up now, with OS X 10.7. They've made it more like the portable iOS from the iPad & iPhone, probably to try to attract those users by saying "you're familiar with it!" But the iOS is good for handheld touch devices. Why the heck would I want that on my m+k, no-touch, desktop computer?)