So what if Riddick killed two Pitch Black aliens? There's nothing to indicate that they are nearly as dangerous as preds, or that they have superhuman strength or durability (though they are obviously pretty fast). Riddick almost died in a pincher attack by just two of them. The preds would probably slaughter the things by the dozens. The one in the first movie lost because Arnold managed to get it into a trap that involved dropping a log that probably weighed a couple hundred pounds right on its head, and it still lived long enough to activate its self-destruct bomb and laugh at him. The one in the second movie took multiple point blank shotgun blasts and had an arm cut off and was still running around and outfought Danny Glover (it lost because it let its guard down while he was kneeling).
What's Riddick actually going to do to hurt these things?
Preds got tricked by a single Army man, whilst Riddick outwits dozens of mercenaries. LOL So much for strategic advantage. Preds was defeated on a samurai duel against an average Yakuza member. One pred got tricked again by a Palistanian soldier, and beat em with a wrench. Never saw Riddick getting his ass whooped by normal humans.
LOL otakus are so out of their heads, I once argued with like ten of them against me, saying that goku can kill all marvel characters, including the galactic busters and all fathers. I showed them a link of Frank Richards, they never replied again.
Basically Cavill played a different version superman, unlike reeves who depended on the quirky, funny nice guy boy scout that we know and loved superman. While Cavill on the other hand had given a hard task to portray an emotionally troubled man, who travels the world to find out who he really are.