I don't think the garment was invented to hide a woman's body shape or having fat girls in mind or even make one sexier... So I disagree with many people here. It's actually very useful to wear under a more fitted suit, it helps with not having to keep on checking and tucking in your shirt all the time - so yeah, maybe it improves a woman's appearance in that regard. (Maybe that's more of a problem for women with hourglass shaped figures though, the tendency of your shirt to go up as you walk, bend down, etc?)
It's not the most comfortable garment in the world (and it can also be hard finding one that fits you nicely torso length wise), but so aren't other tight clothes, pantyhose, bras, heels, etc. etc., and that doesn't stop women from wearing those >___>
I only wear that kinda stuff if I wanna feel sexy... and most of the time that's without other clothes haha. No but really, that thing is hella impratical on a normal day. First of all; what if I wanna pee? And even though it looks nice, most of the time it doesn't feel nice for longer periods of time.