@Smokin Joe
Well, flirting isn't necessarily meant to be an end-all and be-all in itself, though. Many times, it's intended to lead to something more.
That depends on the intent of those involved. At its core, flirting is an invitation to 'notice me'. A guy can initiate it by doing so, or a woman by a look or action that gets attention.
In some situations, that's like fishing for compliments on her (or his) part, and in all honesty, it feels good to be noticed (playfully) by the opposite sex, even if you are attached. (The old 'still got it', without the complications of a deeper relationship).
One of the 'rotten' things we did in college was sit on the hill behind the student union in the spring with number cards. We called it the 'Out to Lunch Bunch Beauty Contest' and rated the young ladies in their spring finery. The lowest grades given were in the sevens, the highest depended on how many zeroes a guy could hold up after the one.
An observation: while a few were offended (or feigned offense), most perked up, stood a little taller, seemed a little brighter in their demeanor.
Everyone gets a boost from feeling attractive, and no more need come from the interaction than that. It usually leads to something more when someone is seriously (consciously or unconsciously) looking for more. Even that doesn't mean someone has to act on that, and it might just expose their dissatisfaction with the situation they are in. What they do about that is up to them, and if that situation does not involve a committed relationship, they can do something about it without hurting anyone. If it does involve a committed relationship, it might just expose what needs work, rather than be taken as an opportunity to cheat. It all depends on the people involved.
Most of it, from what I have seen, is lighthearted interaction without the intent of getting deeper, but then, I have never been one to 'get' hints, so maybe I missed something...