IMHO the degradation of game quality is a symptom of the console boom. This doesnt only apply to NFS, but Undercover is a prime example of whats wrong with the status quo. The effect of this console age is two-fold:
1. Since current-gen console games have a lower rate of piracy than PC games, companies opt to develop for the console as a higher priority since most of the profits are there. Then porting to the PC ends up taking a back seat, and the reduced development cycles of these games in the past few years isnt helping much when there are even more platforms to code for. This leads to badly performing games on PC's which are more than capable of running them at even higher graphics quality levels than the game can provide. Also, it leads to situations like in NFS Undercover where even though there is a huge tricity map to run around in, its populated like a ghost town which was probably a programming decision made so that the lower specced consoles could handle it. Ofcourse during the port, no attempt was made to scale this up, even as an option.
2) This generation of consoles has made it 'cool' for people who formerly mocked 'gamers' to get into gaming. While i have no problem with this, game developers have started pandering to the newcomers by making the bar-for-entry into many games so low that older gamers are not being challenged, nor are being given the option to be. This is seen in the lack of difficulty settings in NFS:UC which is a terribly easy game to complete. And even the much-loved Prince of Persia series has fallen into its clutches. Single enemy battles with onscreen button guides at key moments, the inability to die or make mistakes is an insult to the capacity of gamers, and is pandering to the gaming-infants since publishers are afraid that too high a difficulty setting would put them off gaming completely, thereby losing out on their newfound demographic.
All in all, since this boom is just beginning, things are definitely going to get worse before they get better (if at all). It depends on a lot of factors, one being how quickly these neophytes' mature and wether or not they demand higher standards from game companies. Another is that developers should realize that designing for the PC first, and then scaling down ports for the consoles will always result in a cumulatively higher quality product across the board.
[/rant]
my 2 red cents.