Certain countries have certain art styles and art tropes that come through in stuff they make.
Korea and Japan all seem to have a fondness for anime-ish styles, and have a tendency to also include cute little girls and cute little animal people as playable characters.
Alongside big monstrous giant beasts that seem to be quiet and gentle.
Actually TERA reminds me of FF11 more than anything, now that I think about it.
EDIT:
I found a game called Sorcery for the PS3 (involving the use of Playstation Move, though I think it looks pretty clever) and a lot of people called it a Skyward Sword rip-off in a way that indicated that this automatically made it worse than Skyward Sword.
Now, aside from some people's certain irrational hatred of anything beyond pushing buttons...
People complain about how games have similar concepts in a negative manner. This feels very backwards to me.
If a company makes a game that has a similar concept, they'll be under a lot of pressure to make it BETTER than the game that their game vaguely resembles. (Aside from shovelware games, but shovelware is shovelware and will always exist and there will always be people who buy it.)
When companies compete, customers win. When they compete in the same genre (sorta), customers who are a fan of that genre wins.
Also, no, Sorcery is not a Skyward Sword rip-off. They have entirely different concepts, different form of motion control with different requirements, and so forth. The only similarity is that they are action/adventure games with motion control.