The issue comes from display type, if its a TN panel for example it will not look as good as a IPS or a VA TV.
Granted not all TN panels are bad (my monitor is a TN panel) but color reproduction tends to be a bit of a weakness on them.
And 4K isn't a guarentee for better picture quality, its a resolution not a determination of how good it will look.
I have seen 1080p look better than 4k plenty of times thanks to this factor, companies sacrificing color quality for 4K resolution as 4K technology is still every expensive.
Even IPS displays can be made to be cheap by disabling features like color correction, its all about marketing really.
Thats all 4K is in the end, its a marketing ploy right now until it becomes a standard.
Edited by MadmanRB, 07 March 2018 - 05:59 PM.