I'm going to play Devil's Advocate, but I'm not going to full-on lie and say that Kennedy is a technical genius. He isn't. He's an average wrestler with an average move-set. But that's not what wrestling is all about. Hogan, Rock, Cena, Goldberg, Undertaker, Nash, etc. were all pretty bland in the ring, but they made up the difference by oozing personality. These guys weren't pushed because they were good between the ropes, it's because they were good on the mic, and eventually some of them were able to catch up on the technical side of things by working with other great wrestlers. Today, Undertaker, Cena and Rock have each had a couple of 5-star matches.
I always saw Mr. Kennedy as a similar type of superstar. He would ooze personality, but he was bland in the ring. He made it for that by having a great character, great entrance, mic skills, etc. Some parts of his character were hokey, and of it was up to Ken, he would have been even hokier, but WWE knew how to tune his character in just the right way for him to get over. I definitely saw Kennedy as one of WWE's future stars. Had things gotten differently, by 2011, I bet Ken would be putting on 4 star matches with Punk and Bryan. His ring skills would grow with time.
HOWEVER, the dude was injury prone as fuck. I feel sorry for him, because it might not be his fault that he was born with paper skin and glass bones, but it is what it is. Not only did he get injured all the time, he would also injure everyone around him. After his magnificent start, it became apparent that keeping him around was a risk. And after injuring Cena, there was no way they would allow him to injure Orton. It was time to let him go and I agree with the release.
I doubt he has a place back in WWE. Never say never, but I don't think it would be worth the time or effort to reintroduce Mr. Kennedy and then have him injure Punk, Bryan and Orton in some horrible freak accident involving a mistimed triple clothesline.