WHY DQ isn't popular in America

Hello!Nice to meet you.
I'm a Japanese.
Well...I have a question.
Why the Dragonquest (In America it called DragonWarrior) isn't popular in America?
DragonQuest is most popular RPG in Japan (than finalfantasy).
It's wonder for me.
WHY?
Could you tell me your thinking(opinion?)about it?

Sorry,Poor English.

Akira Toriyama, etc.