One device to compromise. If malware infects the LAN-of-things gateway, it can tell your pillows to play deadmau5, tell the lights to flash, and tell the security system to upload shower-cam photos to facebook.
(But then, computer viruses that just annoy the user with sounds and flashing text are deader than dial-up. Connected home malware would probably wait silently for bad weather, then lock you out and demand 0.25 bitcoin to let you back inside, or steal your amazon credentials when the refrigerator orders more milk, or turn on everyone's air conditioner at the same instant to DDoS the power grid.)