I think the impressive is likely more to do with other facets than the resolution. Without putting your face up to the glass, you won't be able to discern a difference, the human visual acuity limits just don't get that high at a normal distance of a couple of meters or more.

I'd rather have a 1080P plasma than most cheap 4K LCDs. The demonstrators are likely OLED which mean supremely granular conrol of both color and brightness, like plasma used to be. Even nice LCDs have granular backlighting, sometimes with something like a 1920x1080 array of backlight to be close enough to OLED in terms of brightness control.