This makes me think of a commercial that has always slightly irked me. I think it is for Purex...yeah, Purex all in one laundry thingamajig. Anyway, they say something along the lines of 'So easy even he (referring to apparently inept husband) can do it.' Yes, because it is so difficult to pour laundry detergent rather than throwing a sheet of detergent in and men are so stupid that they cannot figure out how to measure and add detergent. But their marketing department knows that there are plenty of women out there who really do feel men are incapable of performing daily household tasks and that there are plenty of men who allow that to be believed.
I think many people are still raising their children with clearly defined gender roles which is where this is coming from. I wasn't raised with that mentality but several of my childhood friends were and they are, whether intentionally or otherwise, raising their children with clearly defined roles.
Many daughters are raised thinking men don't do certain things (primarily around the house and with children) and many men are all too willing to go along with it...."You know I don't cook very well. I guess you'll have to make dinner." "I don't change poopy diapers. They smell." "I can't do bath time, the kids are too wiggly." "I can't do bedtime the kids want you." And so on and so forth and the women go along with it for whatever reason (they think that is how it should be, it is easier to just do it yourself, etc.).
In my household we don't give praise for doing the menial everyday things that need done. Sure we sometimes say thanks but nothing beyond that. If the baby needs changed and my husband does it...great. He is her dad and she stinks...he is plenty competent enough to rectify the situation. If it is a big project then praise is warranted. If my husband replaces the kitchen flooring then, yes, I am going to tell him it looks lovely, it was just what I wanted, thank you for installing it...best husband ever but he isn't going to get that for unloading the dishwasher or checking the mail.
As for rewarding good behavior, so to speak, with sex...wrong for me and my hubs. We have sex because we enjoy it and love each other and we want to keep it that way. Having sex as a reward would cheapen it for us and take out a considerable part of the enjoyment.