If you want an explanation for Skabb, its mostly that he's this really terrible joke villain that takes up a large chunk of an already very short game. You can do comedic secondary villains, but you need to have maybe a bit more to them than "He's stupid and his pets control him", which is a twist that's been done many times. Except its not even a twist and is just there from the start, so there's no joke beyond that.
The best I can compare is Captain Slag from R&C: Tools of Destruction. He's a comedic secondary villain, but he actually does anything throughout the game and is allowed to be a character in his own right. Skabb really isn't a character and is just a boss character for a boss character. Slag is also paired with a main villain who isn't just generic evil man, so there's that too.
And his two fights are both just way too simplistic for a game that has a GoW-style combat system. They're designed like basic platformer bosses instead of anything that actually makes use of the system. I'm not going to call it a straight up bad boss fight because it isn't, but it is a waste of the combat system.
You aren't wrong as far as simplicity goes, but this trilogy HAS done worse in that regard (those bosses you can only go left to right on for example).