Why am I being downvoted? Turning their display into a tv may not be a big step but turning their display into a tv that will replace the current living room tv certainly is.

This is a crucial point. The displays Apple sells are nothing like your average Living Room TV in dimensions, service requirements, or capabilities.

Apple doesn't have the retail floorspace to stock or sell 50" TVs, they don't have experience with cable tuners and all of the other associated crap that distinguishes a TV from a simple display, and they don't have in-home warrantee repairmen; expecting the purchaser to schlep a 50" behemoth to the genius bar for service is out of the question.