Not to ignore the fact that MonHun as a series is violent in nature and can be off putting to some, but I consider its violence to be tame in comparison to what constitutes a "T" or "Pegi 12" rating in many other games. The blood is minimal, and the weapons used are often very cartoon-esque.
As far as animal abuse, the vast majority of what you hunt in the series is done so out of necessity, whether it be for self defence or for resources. That being said, however, sometimes players kill helpless "Kelbi", or this game's version of deer, just because they were there. However, the same could be said for the Mario, Sonic, Pokemon, and other "E" rated series. That, however, opens up a can of worms I'd prefer left untouched for now.
And, as was previously stated, parents are the deciding factor as to whether or not their child plays the game. Many parents ignore the ESRB and Pegi rating system entirely, giving 6 year olds COD for their birthdays. Again, a can of worms.
TL;DR? This is a problem that has long been discussed and debated since the conception of video games as a medium and is present in, though not specific to, Monster Hunter.
