Apparent visual quality in a movie is a function of several things coming together. Resolution is part of the story, but it isn't the whole part - or even really a big piece of it.
Digital Production: First, many film producers are using digital production all the way through post-processing. This allows for more rapid assessment as to the general quality of the shot. Of course, it goes without saying that it is easier to tweak the digital video shots for lighting, brightness, contrast, saturation, etc. - which is abhorrent to most cinematographers, but that's the way it is now. This makes it easier for the visuals to "pop." Most of the time this is 4K resolution, but I've heard of even higher used.
Digital Projection: In the cinema, perhaps the biggest hitter in terms of visual quality has been the replacement of film with digital projection technology. I've heard people mutter about film having higher resolution -- hogwash. The human eye is incapable of perceiving pixels from a 2K source in a normal theater screen (25-30 feet wide) at a normal seating distance; thus, resolution has very little to do with the overall quality (in large format, 4K is a must-have due to the enormous screen size). 896
In fact, the vast majority of theaters do not use 4k projection. There is no benefit for the cost in 90% of houses.
What digital projection brought was better technology all around. Whereas film projection used mechanical means to transport and show the picture, digital has no moving parts. The steadiness of the digital image is immediately apparent. Additionally, the light from the xenon lamp had no optical path - it went straight from the reflector through the film, lens, and onto the screen. If the lamp was mis-focused -- as they often were -- you'd have a bright center and dark corners. Digital projectors have an integrator prior to the light processing engine which evens out the light and ensures uniform brightness across the screen. Colors are more accurate because digital projectors are field-calibrated for color temperature by RGB channel. Last, but not least, the digital image is brighter and more pristine than the film because the specification is better enforced than it used to be (and because digital doesn't accumulate dust and dirt).
Bottom Line: The quality of your digital image depends on a lot of things, with resolution being a small, generally negligible part. 896