Dunno how they acted in the previous games, since 4 is my first MH game. But Raths are pretty much either spinning around trying to tailslap you, flying around trying to tailslap you, or standing still for a bit and then either charging or doing one of the other two things. Or standing still and spitting fireballs everywhere. Or flying and spitting fireballs everywhere
It's not that they're particularly difficult, it's just that all that spinning is annoying to deal with, and then there's all the flying and trying to hit their tail knowing that they might decide to just flip and tailslap your ass with a poison effect and no windup animation. Easy wyverns, just not very fun to deal with.