Now, these are seriously bright, I love the idea but it's a torture to spend more time with. It's seriously dumb that you have no kontrol over the lighting... Anyway, as usual, I tried to deal with the problem by scripting. In Kontakt script you have full control over key colors, so it's no big deal to just remove all coloring. I tinkered this little script which paints all keyboard white, which results in leds going off when you have Kontakt loaded in Komplete Kontrol. If there's an empty script slot in an instrument, I can just load preset script into it and problem solved. Then I started goofing around with key colors, so it would look even more like a Christmas tree. It looks like this...
Just a quick hack job, but you can grab the script here if you like: http://www.fairlyconfusing.net/docs/light_kontrol.rar
Copy preset file to ...Documents\Native Instruments\Kontakt\presets\Scripts or copy paste text into script editor.
As I said, I do like the feature, though in majority of cases you don't need the light-guide or instrument does not support it and there it is anyway. The script solution works for me, and it's is fun for fx flash show.