For her age, Mom's got a rockin' bod.
I'm sure she's had several rounds of reconstructive surgery, and probably some replacement parts. In fact, she may well have the sexual equipment of a teenager*
(which would explain Farnsworth's constant willingness to do the driest, wrinkliest, horizontal tango in future history), and if I was a hundred and eighty I suppose I'd find her about as desirable as anything else.
Speaking as somebody who isn't even forty yet, I don't find elephant skin rugs all that attractive, personally.
*Literally or figuratively. Either is possible in the Futuramaverse.