1 - Advertising. Enix never had a great promotion for their products in the West, while Square used resources in the NES/SNES era that brought better results, then the PS1 era began with Sony putting a massive ad campaign for FFVII (they were publishing it in the West), the Square-Sony alliance made them extremely popular in the West while Enix was conformist with Japan. All that changed with the merger, SE began to promote highly Enix titles like Valkyrie Profile, Star Ocean and Dragon Quest in the West, that's why DQ8 is the highest selling DQ title to-date.
2 - Name. Dragon Quest name is new to the West: Since the NES era, Dragon Quest was known as "Dragon Warrior", that caused confusion. When the merger occured, they registered the DQ name, and that ended the confusion.
It will be very interesting seeing DQ9 numbers in the West...







