I hope this doesn't come off as snotty: it is a genuine question.
Why use a lingerie bag when hand washing???
I use a lingerie bag with my non-molded cups and throw them into the washing machine (a front loader). I hang these dry over a rod with one cup on either side of the rod. I probably wear the bras 4 times before washing.
For my molded cup bras I hand wash in the sink using Soak brand lingerie wash (unscented:I have allergies). These I dry on hangers with the straps through the strap hooks on the hanger and done up: as though the hanger were my body. I probably wear the bras 5 times before washing: I should do this more but I"m fundamentally lazy about hand washing.
I don't think my bras stink. I think I get reasonable wear out of them before they "die" so I don't think I'm harming their longevity. The wear points on my bras do discolor in such a way I can't wash the marks out. Maybe that wouldn't happen if I washed more often?