The Von Matrices Out of curiosity, I'm not sure why an option for different pixel aspect ratios within a monitor is necessary. I've never seen a DVD/BD player or any video software that cannot convert anamorphic content to work on displays with square pixels.

HD content isn't really the issue as far as I'm personally concerned. BD/DVD - as you say, are already scaled for monitor use. If that were the only input source then the only issue is the method of upscaling and its quality (since most- if not all- 4K content requires upscaling/upsampling). This in itself is more likely to produce visual artifacts and/or blurriness if a simple 4:1 pixel mapping is utilized - something that could well distinguish "cheap"4K monitors as it does 4K TV's. Not all upscaling is created equal since the more expensive option involves use of algorithms to blend the upscaled pixel map, something that seems to be missing from the lower priced 4K panels (just as cheap Korean 1440p panels are often non-scalar to keep costs down)Having a quick browse for upscaling/pixel mapping throws up a bunch of long-winded PDF's. There are a few Youtube (company sponsored) vids covering the topic, but you'd need to browse a dedicated AV forum for uncompressed (compression artefact free) comparisons