OP, while I don't like Kofi, and agree with most of your well made points, I do believe Kofi has value to the WWE. For you see, over mid card babyfaces, Ryder, Santino, Kofi, Rey are important, when used against the main event heels, in a business where the Heels find it so hard to get clean wins, and the top faces rarely lose clean, people like Kofi are ideal for jobbing to the heels, like he did Del Rio this week. During Dbry's worlds title run, the only people that tapped to him were Kofi and Santino, hence I think he has some worth in the company.
While Jericho's recent run saw him put over as many faces as possible Kofi was one of the few to actually job for Y2J in some very well wrestled matches. Goes to what your saying, he has a role to play.