Incidentally Buenchico, the reason many devices can only be connected by wifi is due principally to cost-cutting exercises by the manufacturer. They simply can't be bothered to modify oriental manufactured equipment to accommodate RJ45 sockets on the PCB or cut the corresponding mounting holes in the device chassis. Small device footprints have become the norm.
However, you need to be aware that the general public nowadays can't be bothered to faff around with connections and on-screen menus etc and want everything to be plug and play. Wifi connectivity by and large meets this requirement. that's why it is endemic everywhere often to the detriment of the more reliable and secure connections that are available.
I'm glad I've clarified the definition of Smart TV's on this thread as no one seems to have any issues with it now that I've explained.