Is the game becoming too metaphysical for its own good?

[Lersayil]

I think you misinterpreted Urianger's line in the trailer. He said:

"What sayeth Master Matoya? "You can embrace your fate, or defy it. But you cannot deny it.""

He refers to Matoya's teachings of the past - he didn't refer to Y'Shtola.

In the Japanese trailer its a lot more clear and... yeah Urianger totally calls her Matoya.