To directly answer your question, if the guy's pulling in 250k a year (I'm certainly not) and she's pulling in 30k, and they have small kids, it's probably not the best use of her time.
If they're just scraping by through no real fault of his own, then it's a quality of life issue. Are the husband and wife as a team willing to scrimp on things w/out having a crap attitude about it? Are they willing to take responsibility for the damper on their retirement this may well cause?
A lot of women work a job called "housework", they just don't get paid for it.
Another thing is perception -- if she doesn't have a job because she is uneducated/ignorant/lazy and can't hack it, that's one thing. If it's because she makes a considered decision to devote her energies elsewhere, that's different. In that sense it's really more about the woman you're with rather than the job she has.
I gotta admit I wouldn't be too impressed with a woman (or man) who just wants to hire maids and nannies and sit around doing nothing all day. And if she won't work, any complaints that I didn't make enough money or any pressure to ask for a raise would get old *very* quickly. But of course that's not the question you asked.