Tube (drop) control arm Pros and Cons?

[heavychevy79]

I was wondering why more people don't use those lower tubular control arms/a-frames?
I think most of them are rated for a 3" drop, and those are what I'm
interested in, so I would like some input as far as if they drag on bumps, or
do they not work good with drop springs, or if they fit with 15" wheels?

Thanks guys!