I watched the commentary of the pilot the other day (yes I bought the dvd!)and they said that they weren't sure about Serge and someone (cab't remember whtehre it was Moore, Eick or the director)didn't want to keep the character in the final cut, but the guy who did the voice fought for it.

Fortunately they changed their mind. Caprica wouldn't be the same without Serge Graystone!