If you look back to the old days (let's take one cliche example, Queen Victoria) women have always had boudoirs. What fascinates us as humans is the unknown or limited, exclusive information. The reason V.S has its name is due to the desire to exploit the secret nature of Victoria's collection.
Lingere is clothing that we own, but do not share with most people. I have a whole chest of it in my very cramped New York apartment. Though its a sin to dedicate that much space to things you wear only occasionally, it makes men feel special that you're wearing it for them.
Not only that, but when women put on lingere, they know they're being sexy. The confidence is boosted. When you feel sexy, you act sexier, and this, in turn, generates a much more excited response. Especially if you feel insecure naked, lingere can help those who don't want to give it all away, but still be wanted and desired sexually.
Also, it's a tease. Wearing something that exposed the nipples but not the private areas can be enticing for others. It's like slowly unwrapping a gift.
There's also the more negative but still realistic answer that media and our society have brainwashed us into thinking someone wearing lingere is someone who is about to put out and therefore, it's a *ding!* moment.
Either way, if you see someone in lingere, you're pretty special, and you're probably going to get something for being so special. Who wouldn't get excited?