I see the problem of the door access style being far more than is needed in many, many, commercial applications. Yeah, all the bells and whistles, card readers and such, can be handy in some cases, just being able to see and talk is what I think is the overwhelming case. The problem with the current crop is they are WiFi which just isn't very reliable for real surveillance systems. PoE would solve the whole thing at a minimal cost increase for the doorbell but would require a CAT, or two, to the door to work. Being most people are too lazy to run that cable, or don't want to pay a professional for the installation, or they are ignornt of the problems when using WiFi, my SIL is a prime example, the WiFi will still be king.