Most cinema standards recommend around 45 degrees field as ideal. 1080p can be resolved in 32 degrees. That's probably why digital cinema is 2k. 1080p is just good enough to meet the bare minimum to meet the farthest distance recommended, it's not ideal to support the ideal recommended or the closest recommended which is around 60 degrees field.
So how far back are you from your 50" screen for typical viewing ?
Actually, I currently have a 24" gateway LCD monitor as my "television" -- it doesn't have a tuner nor speakers, but all those are external components in my setup. I used to have a 34" CRT, but didn't like the amount of space it took up. I also didn't want to get a large LCD for the same reason. I sit about 5-6ft away -- and realize it's a little too small for that distance. I would ideally get a 42" screen if I wanted to invest in a real TV.