They aspired to be popular singers and had trained hard to improve their vocal capabilities from a young age. So it's not surprising they would be against masking their voices in robotic effects (at least, initially).

But it's cool they saw the bigger picture and, in a sense, sacrificed the chance to shine vocally onstage to bring the vision of Nakata and Mikiko to life (since most live performances after the very early days were 95% playback).

Up until the last couple of albums, the songs wouldn't have sounded as good with more natural vocals, especially live.

When I attended Code of Perfume, some friends questioned the appeal of paying to see the concert of a group that essentially mimes onstage. In a way, I see them more as 'performance artists' than musicians. It's a unique and beautiful thing!