It was the answer to the problem of
Spoiler:They were having to make Peter not know what to do with all his power... and now
Peter having over a dozen powers and being the most 'special' character on the show- taking it all away.
Spoiler:
he doesn't have to worry about it.
Sylar was feared as a villain because of what he could do; kill you and take your power, violating you in a highly personal way and ending your life.
Linderman was feared because he was a mob leader and had a great deal of charisma behind him. I liked that Linderman did not have some lethal ability; the irony of the man who could heal being the one who wanted to blow up New York.
Adam was feared not because of what he could do, more because of what he wanted to do. Unleashing the virus and wiping out the world population is horrific and slightly psychopathic. Same thoughts with Adam; the man who can't die is the one who wants everyone else to.
Arthur... yeah, it's his power... though it makes sense as it
Spoiler:
connects to Peter quite well; Peter is (or was) v2.0 of Arthur's ability. Same with Sylar, being able to figure out how to take abilities. Nathan being the odd one out, of course, but now we know he wasn't born with it...