You have to be careful with using the word 'scripted'. Some people believe every single word, action or event in WWE is in a script, not the case.
The malice and rivalries are there, it's just they're based on more larger than life things than MMA. For example, the nepotistic Edge screwing the fan favourite, all-round American hero Batista. You have to see wrestling as bigger, the guys are playing characters and creating storylines, if you miss that then wrestling will never be anything. The biggest storyline in wrestling wasn't based around KOs, cage fights, (I find MMA boring, as do many WWE fans, it's too different) it was based around the working class guy rebelling against his overbearing ******* of a boss, hence Austin/McMahon was so successful. If you look at the storylines, you'll see all sorts of problems writ large, from Hispanics trying to make it against rich Americans, to an unsually violent Irish leprechaun beating up a metrosexual with a shillelagh(ok that's an exception lol).
We all know WWE is planned to a decent extent, we know the match finishes are planned and so on. In short, we know. And yet we watch it. Figuring out why isn't really that hard if you look. You get interesting characters, over the top events, a genius/madman of an owner who's not afraid to say anything or get beaten up, hot divas (haters always forget the divas) and great memories. I understand why people watch MMA, but I watch WWE. And just to reiterate, we know it's not real.
A lot of wrestling fans would find a boxing match boring for example. There's no exaggeration, no over the top characters, no precisely defined heel or face, no injustice etc. There's no legend in a long black coat, an Italian immigrant who needs to learn English, no JR to call the action. Put simply, what you see is what you get. If you suspend reality (like every time you see a movie) for a while, the appeal of wrestling becomes clear. It's not about reality, rigid rules, real people, pure athleticism or knocking out an opponent.