On top of the fact that some distributors (Warner Bros. for example), simply don’t bother enhancing the image (digitally or otherwise) because they are cheap, cheap, cheap.

simply put the camera’s back then were junk, you can only enhance an old movie so much before it looks like a cartoon

If you are talking about the grain and gritty appearance of the old movies, then some directors want to maintain that old school vintage “feel” of their films. It adds to the experience. Making them crystal clear would be like watching a completely new movie, in their eyes. Grain and grit are good!

Picture quality is limited to the original plus some digital magic to clean it up a little bit. Theres no way to magically add a bunch of pixels to a frame that were never there in the first place.

its the camera’s they used to film originally that is the problem and cannot be transfer very well to blu- ray but the spahgetti westerns look good just check this out