thats because 12000k lights are higher on the chart and produce less lumens. think of it being like a black light. it might be a 60 watt bulb but it won't illuminate a room the same way a lower k light will.
quick quote i saw from a google search that explains it good
Color Temperature Explained:
Color Temperature: 3000K
3000K emits GOLDEN YELLOW color and offers superior *********** power during adverse weather epically in dense fog. The applications of the 3000K kit aim more towards secondary lighting apparatus such as high beam and fog lights. This is the color temperature that will catch all the attention on the road.
Color Temperature: 4300K
The light appears fairly white, and has light yellowish hue when reflected off the road identical to the OEM HID equipped vehicles. It is ideal for customers who does a lot of back road or canyon driving and need the optimal visibility.
Color Temperature: 6000K
6000K emits pure white light with very slight and barely noticeable tint of blue and purple. This color is for customers who is looking for pure performance white while improving the looks of their headlight.
Color Temperature: 8000K
ORACLE 8000K has an approximately 3000lm output, which is about 3x the light output of the traditional halogen light and slightly less light output compared to the 6000K. While it has a bit lesser light output, it emits bluer light than the 6000K.
Color Temperature: 10000K
ORACLE 10000K has an approximately 2800lm output, which is more than 2x the light output of the traditional halogen light. 10000K produces a deep blue light output approaching violet and the blue is noticeably deeper than the 8000K.
Color Temperature: 12000K
This color temperature puts out a deep bluish violet light and is deeper colored than the 10000K. It is for customer who is looking for the most extreme and most exotic looking light output.
Common HID Misconceptions:
Higher the K (Kelvin temperature) the brighter it gets- Not True, the Kelvin Scale measures color not brightness. The brightness is actually inversely proportional to the light output. 4500K HID is technically the brightest and the further you increase or decrease from 4500K the lumens (visible light) will slightly decrease.