Blame the new direction the game went in as of DOA5 Ultimate. They inititally tried to appeal to westerners with vanilla 5, it didn't work how they wanted, the japanese ate up the fetish dlc then Marie came out so now they focus only on the japanese market.
It's completely intentional @King Anubis. The average Western gamer doesn't give DOA the time of day so they focus on the Japanese & Asian markets more. However, DOA5LR's roster is still pretty diverse (which is helped by the 36 character size). Also take note that DOA5's 1st new characters, Rig & Mila, were intended for a Western audience.
Tekken on the otherhand does appeal to the American audience, including the 'dudebro' crowd. Interestingly, Tekken has tried to appeal to the Asian demographics since around Tekken 5, with characters such as Lili, Asuka, Alisa, Lucky Chloe, Josie (and I guess older characters like Xiaoyu can be added).