Personally, if I ever come across non-voiced VNs, I'd rather read book with illustrations each page LOL (particularly Phantom of the Opera Illustrated classic if I really need that 'imagining guide' at least I'd know I'm on the right track). But then again, I would also see myself listening to audio books (much engaging!). So to just completely summarize the blabber, I prefer the Visual Novel to be package-wise (voiced as well), besides, it's among the essence that create the Visual Novels' existence (particularly their appeal ;)