For DOA, it makes sense. She'd be gimped as all hell without her Wicked Weave... perhaps even moreso than Hayabusa. In a game like Ninja Gaiden, she'd be more fitting.
It's impossible for DMC since he worked on DMC1-3 when he was still with Capcom, he left afterwards to create Platinum Game studios so he doesn't have access to DMC characters due to the characters being under Capcom's label.
He does get spammed a lot from what I hear. Particularly the Super Smash fans because she was included in that game. Also didn't know about DMC2, the game was so bad that I didn't even check for people who made that one.
Plus Helena is just a mustard blonde slut who uses the whole oujou stereotype to facade the number of "microphones" she's "sound checked". :-| Right PB?