For many women, what you are describing is true. However, they don't have to be young - women seek approval and affection irregardless of age. Perhaps when they are 35 they label themselves "liberated", but I know plenty who are actually looking for a husband, yet they have fallen out of favor in the regular dating game and sleep with a lot of men in a hope to ensnare one of them into commitment. You see these women on holiday - very provocatively dressed (as it is the only way to get attention in your late 30s), so much more 'experienced' than younger girls - which can be a preference of men when it comes to sex, but not in terms of relationships.
So yes, sometimes low self esteem and promiscuity goes hand in hand. I wouldn't say self worth - it gives the idea that a woman is born with a certain amount of points and every time she has sex she loses a few of them. We were made to have sex and people do, so the entire "she sleeps around, she has no respect for herself" is mostly something you hear from jealous females or guys that aren't getting any. What I do agree on, for both sexes, is that sex can be an instant refill of approval. Women may want to go home with a guy if they are hung up on another, they are feeling like crap or they want to feel attractive. Men do the same thing - I don't know how many times I've heard guys say that if you're feeling down after breaking up with a girl, you go out, get hammered, and try to get another girl home. It is the same concept, but somehow guys make it out to be less sad and pathetic when it's about them.
So yes, sometimes, for both sexes. Sometimes a person is not looking for a relatonship, sometimes you meet someone you get along with but who lives somewhere else or there is another obstacle to a relationship. There are many enough reasons why people behave like they do, and honestly, I don't care too much how others spend their sexual lives. For most women, the main reason why we attach ourselves to one guy (apart from the hormones and stuff) is that it takes more for us to have great sex and there is a huge chance that bringing a random douche back from a club, will not create a great adventure. So for most of us, sleeping with the same guy several times (whether it'd be a relationship, lovers, fwb) is preferable, but some think otherwise. If I see a young girl dancing in a bikini on a table, it is probably just a faze. Sad for her, but it's not really up to me to stress over.