The WWE has given him several of those storylines. The problem is that the actor portraying the character just doesn't do a very good job of playing the character, especially when it comes to his in-ring work. It all comes down to the fact that Kane is just not a very good wrestler.
I saw someone mention that he has a trademark off-the-top rope move. So? Who gives a damn? I could find a ring right now, and do one off-the-top rope move 85 times in a row. That wouldn't make me a good wrestler though.
The fact of the matter is that Kane sucks. There's no way around that fact.
He's right you know. It's so common these days to blame "creative" for wrestlers like Kane. Saying that they've made him look bad, weak or not credible. The fact of the matter is Kane is out of shape, slow and can't even go 15 minutes without looking long past his sell by date.
How much more can creative do for him? Someone said that Triple H was just two years younger than Kane and look at how much better physically Triple H looks than Glen Jacobs.
Kane is no better atm than guys like Chuck Palumbo or Snitsky, he is merely surviving off name value as a familiar face from the attitude era. He is no Undertaker. His only purpose now is to try and put over some mid-card guys, but the shape that people like Ted Dibiase are in compared to Kane makes Kane questionable as a veteran worth going over.
A sad fact but a true one.