I would imagine that there is some Straight To Hell clause in their cockamamie religion that forbids that. These polygirls seem to run on spawning as their only purpose in life.....well, that and servicing the stud in the process.
I think Chloe does most of Jen's fancy clothes because 1) she likes the styles and 2) Chloe knows how to fit Jen perfectly. I seriously doubt she'd use Kleinfelds - it's more likely she'd have Zoey's dress made by Chloe as well. Nothing off of any rack would ever fit properly.
Watch a few episodes of Escaping Polygamy and you'll see that is does still go on. One thing that always made me gag was hearing that the homes all smell like rotten food because the kids have to dumpster dive to feed the families.
I'm thinking his obsession with Robochin is more that she's making herself unavailable as much as possible. She sleeps until noon and when he's in bed with her there are one or two co-sleeping kids. Absence makes the heart dick grow fonder and all.