I think you're all missing the OPs point here. Everyone likes voiced quests, that's not being argued. OP is saying that they may be hampering (financially and organisationally) ZOSs ability to push out new content. I'm not sure this has to necessarily be the case though. It's only an extra step, having someone speak the script aloud, and there are plenty of voice actors out there. At any rate, I think there are other more prominent reasons why ZOS is dragging their feet with new content.
I guess the title of the thread is a bit misleading. It should read:
Fully Voiced Quests Only: A good or bad thing
I'm not saying there shouldn't be fully voice-acted quests. My point is that if there is a requirement that they *all* be fully voiced, then that severely limits the amount of new content they can add