Orly, Well i guess thats why they are called fog lights. LOL
I currently have crapstar 9006 lows and stock everything else. I love how bright the high beams are! But i normally drive at night with my factory fogs on as well. Maybe once i get my HIDs done i wont even need the fogs on anymore and i will get the yellow ones for better "fog" vision.
The yellow light in inclement weather (namely fog) is far better than white light. It doesn't reflect back into the driver's eyes.
I had amber fogs in my MB 300D and they were amazing in foggy/rainy weather. Much better to see with. It is a completely different yellow than halogen.
That would be a good reason to not need the 3k lamps... it gets foggy here though so they will be nice to have.
They are def fog lights too. That is what the owners manual, and the service manual calls them anyway. From the factory they are designed to point low and wide, to penetrate through the bottom of the fog. Running lights are made to compliment your headlamps and point farther down the road.