I won't try to assume how much extra work it would have taken and I'm not defending it. I'm just saying, the UI works just fine, whether it is missing features you want it to have or not isn't the issue.
Ok so I can accept you think its "fine", only because the few things that are objectively "unpolished" or "clunky" are in reality fairly minor. (eg. Favourites browser lack of "Back" or ESC) - its annoying but I can live with it
I can also see why people think it's been "consolized" and why this is a negative thing - the menu funcionality was not designed for a mouse.
Maybe that wouldn't be a problem, but unfortunately there is evidence for this being a bad thing in how some menu's act. (eg Voting menu, fighting sometimes to pick what you actually clicked)
I am upset because they over-simplified some basic options out of this installment of the game. I do wish UT3
replaced any need to still play UT2004 offline (beyond the sake of playing it as another game that I like) - I still play offline UT2004 because of just a few basic bot options which keeps it interesting enough.
Basically - they should approach it a bit differently next time. Making a menu system for the PC and console separately would probably do the trick.