A wife should be beautiful inside and out for her husband. If she feels good in sexy lingerie, then be happy you have found a woman that wants to make you happy.
That being said, I've always been a long, flannelette nightgown wearer at night, and my husband has no problem with that. I just know that my metabolism is slow, and these long, cold winter nights make cuddling in bed a bit special, no matter what we are wearing! LOL