Projectors are nice if you have a huge blank wall. My TV needs to go off to the side due to the layout of my living room, the fireplace is the focal point of the room. Plenty of other rooms the TV has the best viewing angles from a corner. They can't replace TV's in all situations.
(I also prefer the picture quality of my plasma TV over a projector... But that's personal preference. Too bad plasma went the way of the dodo)
In some cases, you can use a screen, even in a corner. But yes, projectors and TVs have different roles, even if one of them is a privacy/security risk.
