I'm sorry but if we were to remove these games the xbox sales would greatly decrease.I couldn't care less if they were the most famous games ever made. I obviously don't like them or I wouldn't want them to die.
And I agree Madden and other EA Sports games are really stupid since it is all the same, but Halo is the most overrated game EVER. halo just seems so boring to me. All there is in it is killing. Same with Grand Thieft Auto.
Of course all sports games are going to be similar. Their sports games after all so you can't really expect them to throw in some crazy modes etc. However they have been changing them up a bit. In NHL 07 they introduced the "Skill Stick" which allowed players to control the stick of the player they were using thus making the game more fun and challenging. EA has also said they were going to improve on it with NHL 08 as well.
To be honest when it comes to sports games all you can expect to be changed are the graphics, rosters, teams and the gameplay. Other than that don't expect much to be played.