Actually they are trying & experimenting a lot by publishing games. Most Wanted succeeded as it had a super story 
Plus challanges were awesome Then they tried Carbon where they put Team Racing (partnership) like real life racing but it failed miserably as it had no story at all & no cops were in action 
Most wanted had 15 top racers to beat while Carbon had 4 !!!
I hated Pro Street as it had only some race days & when I logged in the first appearance of the game was not impressive at all. First impression has a lot of impact in liking a game. Was ProStreet a DJ racing game? I won't say Undercover had a bad story but it seemed to me the game took too longer time to finish. Drag racing were not quite good & I am missing Drift all the way from MW. There were some challanges like "staying ahead for 90 secs" or "Staying ahead by 1000 ft" but they were not quite upto the mark. 15 levels were alright with MW & i don't know why they had gone for 18 levels in Undercover. Upgrading options for the car were not also good. Don't wanna talk about Shift as I didn't finish the game.
I'll see what they have to say with WO
@Tanya: Why is it NSF for you always ?