Since money (as a concrete abstraction) has become a symbol of survival and power, as a sign of the "alpha male"--and also considering the unusual aspect of femininity in human society as a method of structuring and organizing the female gender toward a certain manner, and toward a certain man--then one can expect women to be attracted to money: it's a sign of security; the big green (or multi-colored nowadays) faces are an icon of stability. Those guys are dead, but they feel so alive when they're folded neatly in my wallet; and how I pine bittersweet when they leave my possession in exchange for another prize of equal or lesser quality.
Yet one must never forget that money (though it is a measure of success and would lead to better things in life) cannot be the most satisfying thing in one's life. The alpha male has the inheritance; the beta male has the providence. One supposes that no man can be both, at least not to any particular woman. Even if the man has the right genes, that still does not mean that he is able to provide capably for his wife/lover/paramour/concubine. And even if the man can provide (with all the bloody money that money can invest), does that mean that the man is the proverbial "knight-in-shining-armor" with the perfect set of genes behind that clanky chain mail? Maybe one can be both. But who's to answer that question? The man?
As for the original question about legal prostitution, one would then have to consider the reason why marriage and other long-term relationships might be seen as ritual exercises for the sake of financial security and human survival. The idea of prostitution is accepted in almost every "highly developed" culture in the world, though it is hardly condoned. The idea of sex is seen as both a sacred and profane act. (Just as it is easy to say that the restroom is both the cleanest and dirtiest room in a building.) Sex--at least back in the "good ol' days"--was seen as either completely sacred (in the ritual of marriage) or as completely profane (in the underhand dealings of brothels). Nowadays, fewer and fewer things are seen as absolutely taboo.
In my honest opinion, people (not just men, I should hope) require release from stress and daily life (Marvin Gaye's titular "sexual healing"), but to make a big fuss about it--as many people would about the issue of legal prostitution--would take away much of the pleasure of doing something that is hidden or secretive. That's the reason why man and mistress meet in a random hotel room during the day; or the reason why man and prostitute meet in a random back alley during the night. The legal brothels in Nevada, by the way, are distant enough from any major city that such practices (usually considered taboo) have some level of "aesthetic" distance from those who find it abhorrent (or at least find sexuality sacred).
Now, for those who find sexuality in some level a sacred thing, then the whole idea of money--filthy, dirty, skunky-rich-green money--involved is just bad. Terribly bad. Now, for those who find sexuality as neither sacred nor profane, but as the only way to procreate, and usually as the ends for survival of the species, then by all means money is important--perhaps not completely integral, but it's going to be a factor (no bones, figuratively, about it). That's what the barter system and capitalism will do for you. But let's celebrate with a round; drinks are on somebody. And my eye is on the lonely brunette with pouty lips and a Guinness. Now if only I can buy her another...
"I like refried beans. That's why I want to try fried beans, because maybe they're just as good, and we're just wasting time." - Mitch Hedberg (1968-2005)
"Football is about if you want to run and fight for each other, if you really want to play that killer ball." - Robin van Persie, Arsenal FC