well, first thing I would point out is that, in both genders, you have people who date for the wrong reasons. Perhaps womens reasons are sometime more monetary, but really, everyone's different.
Yes, some girls play around; They enjoy the power and it certainly helps any insecurity issues they may be dealing with.
As for why they would rather marry a person who makes more, well, I would say that that's a product of both nature and society. Men are traditionally the protectors and bred-winners of the house-hold and even if that doesn't still ring true in modern families, more often than not, the mind frame is still there. As females in packs of wolves for example like to mate with the Alpha, women like to date the more successful of the metaphorical pack because they want the security and in some cases, what they feel is the more advantageous gene pool. Security coming from the knowledge that they and their children will always will less likely be destitute, and the gene pool .. well. I've just gone to one anthropology class too many.. I'll leave that alone.
I'm not saying that love isn't important, but the fact is that, most women know that love.. It just rarely last forever, and at the end of the day you need something warmer to hold onto than a memory. Besides, love gets shaken when financial issues become a real hindrance of the family.
Good looking- well again anthropologically speaking, women subconsciously pick mates with more symmetrical features, because it goes hand in hand with the want to produce better offspring (as well as subconsciously registering as superior genetics).. but getting off that trip, uhmm, we all like to be physically attracted, but even though that's the first thing we notice, it's certainly not the last. Many women don't in fact look for looks.
And finally to conclude my overly long answer :P, You forget that everyone has feelings, not just men. Hell, most of the time it's women saying the same thing about men you're saying about women. Sometimes, when you get hurt so much, basing a relationship purely on love seems not only foolish, but dangerous. The other factors that come in become almost an insurance you know, like, he cheats on you, but at least you have food to feed your kids and money as a means of distraction as opposed to him cheating on you, being in financial straights.. and well.. not.
and that concludes my rant-like answer.
I hope it works out for you sweetie.