These would be much worse. They're essentially an array of tiny LEDs and a consequence of the distribution of LED forward voltages will mean that some of the LEDs are going to hog current and others will get less. This will lead to bright spots, and the human eye is actually very sensitive to this. You get the same problem with OLED displays and people have complained a lot about the visible noise on OLED phones like the Samsung Galaxy Nexus.
Usually what you do to solve that problem is chain a bunch of LEDs together in series and then those groups together in parallel. If your process technology is +- 5% then chaining 5 LEDs in a row will even out your average error to +-1% instead. Which makes a big difference. Of course, if they don't do that then you're right that there can be problems.
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These would be much worse. They're essentially an array of tiny LEDs and a consequence of the distribution of LED forward voltages will mean that some of the LEDs are going to hog current and others will get less. This will lead to bright spots, and the human eye is actually very sensitive to this. You get the same problem with OLED displays and people have complained a lot about the visible noise on OLED phones like the Samsung Galaxy Nexus.
Usually what you do to solve that problem is chain a bunch of LEDs together in series and then those groups together in parallel. If your process technology is +- 5% then chaining 5 LEDs in a row will even out your average error to +-1% instead. Which makes a big difference. Of course, if they don't do that then you're right that there can be problems.