They get paid millions to play a game. Part of that contract is for acting as a role model for the millions of children that look up to them and want to be just like them. I'm sorry, but if they do not want to be held to a higher standard than the average folk, than find a different career that doesn't pay you millions of dollars per year.
Besides this, not biting people has nothing to do with acting differently. If someone was irritating me at my workplace, and I bit them for it, I would be charged with assault and possibly spend jail time, or be committed to an asylum. Biting is unacceptable in society, and also in a sport, this is objective. Unlike the subjectivity of determining the intent and degree of hard tackles, and flailing elbows that most often could be argued as non-intentional. Biting is intentionally malicious, no matter what, there is no subjectivity there. Minor bites are not allowed, major bites are not allowed. There is no grey area.
Stop acting like he shouldn't have known this was coming and that his ban is ridiculous. He was banned 7 games and 10 games for the first two offences. He's a complete moron if he thought a third biting offence, and on a bigger stage, where the entire world is watching, wasn't going to garner him a bigger ban than the first two. 15 games was going to be an absolute minimum. And they gave him about 23. Seems appropriate to me.