It's intensely irritating when people write things off as "just of a rip off of X, Y, Z". It's also incredibly lazy and devoid of any kind of critical thinking.
The concept is nothing new at all - and? Do you think every single other book written / film ever made is a completely original idea? Things can be a) not original and b) valued in their own right, all at the same time. That's not to say that there are no original ideas left just that...it's OK if a concept is re-used as well.
Battle Royale is just brilliant. IMO, so are The Hunger Games. There are many similarities. But there are differences too. As far as I recall, BR was set up as a deterrent to what was seen to be an increasingly violent and anti-social youth - an extreme pre-justice for the Japanese government in that story.
The Hunger Games are set up precisely to remind the population that they are completely under the control of the government, following a long history of repression, rebellion and civilian defeat. That they can set these games up and force the population to watch their children killing each other, because that's how much the government has control.
As for not liking them, well you're entitled to your opinion. You're not unreasonable about that. But they are well written within their genre. They promote difficult themes and navigate through very dodgy moral ground, where there is no simple right/wrong, truth/lie option. They are intelligent, and I would be happy for my future teenagers to read them. I read LOTR at 11 yo, The Stand at 12 - through my young teen eyes, I was able to discern the same murky moralities, the reluctant complicity of the protagonists and questionable actions of characters where there is no steadfast answer to the moral/ethical questions posed that The Hunger Games offers.