There's just too many quests. I started trying to play like I play single player games listening to all the dialogue and trying to immerse myself in the world, but there's just so many pointless little quests. Rather than a few larger more involved quests with dialogue exposition at key points we have dozens of Hi I'm such and such, here's some details of my life, now please go do some simple task for me and then come back. Rinse and repeat. I just got sick of it and started skipping the dialogue and relying on the journal and waypoints to direct me to what I should be doing.
It is a symptom of how this game is failing for me. For me full voice is fine if I have deeper more involved and less frequent quests that I can explore at my own pace. The Standard MMO quest model which ESO follows is to use quests really as just a task list to move the player around the world and reward them with xp. So you get loads of them, most of which are pretty much meaningless. There's no need for full voice because the story is just there for the sake of it. The dialogue becomes a barrier to the real purpose of the quest which is to be directed to some content and get the xp reward, so people just skip over it. Like many issues I have with ESO it boils down to the fact they made a standard MMO then slapped some elderscrollsness over it.
I wonder if they put a monitor into the code to see how many players end up skipping the dialogue, would be a very interesting statistic. I'm sure there will be people who sit and listen to it all. From time to time I still do if a story peaks my interest. But pretty much all the MMO players I know would be skipping it just like they skipped the text dialogue in other games.