Anyone who sees the hyenas as evil, in my mind, has an extremely simplified "black and white" perception of the world. Ultimately there are no good guys and there are no bad guys; there are things which we perceive as good and bad, but just because someone does something bad doesn't make them "evil", and just because someone does something good doesn't make them "the good guy". Everything is varying shades of grey.
While it's easy to perceive the hyenas as evil--they're definitely portrayed as antagonists in the film--one has to understand that what they're doing is directly a subsequent result of the deplorable conditions in which they're subjected to constantly. They're just trying to keep themselves fed, doing whatever they can to survive. Of course, that's not an excuse and doesn't exempt them from the consequences of their actions, but it doesn't make them innately evil.