As a side note, 'Etta would want red lyrium, as it's used to power her battle harness, but that's not something she'd be willing to admit to the rest of the group. That means she has three reasons to head underground; red lyrium, dwarven artifacts and golems.
@vancexentan While I fully understand your arguments against using the Deep Roads, how many of the other characters have actual experience with it? 'Etta only knows it as the stuff her family dug up out of the ground which was very useful for powering her inventions, and I don't think any of the others would've had enough contact with the stuff to understand the risks.
At the moment Gerald is coming across as a raving madman, screaming out long unbroken rants about how dangerous the Deep Roads are, but not really being able to convince the others due to his approach. Perhaps if he calmed down a bit and explained what the problems with heading underground were in a more measured way he'd be able to change their minds? After all he's only just arrived while the others have been battling Red Templars, demons and Fade-touched nugs alongside the Inquisition for the past few months and think they can handle the situation.