They are redoing every single spec in the entire games talent trees, PVP trees, Build 36 weapon talent trees and Balance it with specs and make sure it's fun. Tiered CM tuning, 4 raid modes and flex tuning for 17 bosses, a large world with MORE to do similar to mop, PVP honor system rework, Profession overhaul. They have WAY more to do under their belt then just build continent terrain. It's going to take a long time when you consider what actually has to be done.
And why do people post the same stuff here and on the official forums? It's annoying that both forums are almost doubles these days.
People post it on Blizzard's forum because that's where feedback goes if you'd like to see it possibility implemented in some form.
People post it here because more people can respond and provide feedback as the forums here don't require an active WoW account or you to be in the same region as the poster.
As for the UI, I think it look's nice. Though not necessarily saying we need a new UI, but I would be surprised if they changed it to match the style of the Mount/Pet and LFD/LFR tool.