I think they are just the latest fad. It started as a way to set the rich folks homes away from the regular folks. Now I think it is seen as a quick way to act like you have a more expensive house. I don't think there are any 43 cent devices but they are getting cheaper.
The first ones I installed were in the bathrooms when I retrofitted the GFCIs. At that time combo plates were hard to find. Once my wife saw them, I was replacing all the switches. For some reason the receptacles don't have the same allure. I was able to keep the round ones (mostly because I convinced her they didn't make commercial grade decora).
