Guess I am biased on this, but really the Ruby Red/Hazelnut combination is fantastic. I've received a lot of compliments on it. I like the Hazelnut since it is a bit different than the usual black, grey, or tan interiors so common in most cars today. As for the floor mats & floor board -- no, they are more of a black color and it offsets the hazelnut quite nicely. I think if the floor were hazelnut, it would quickly show all the dirt, so the darker color on the floor suits the interior perfectly.
Totally agree on the hazelnut interior. I have tuxedo black-hazelnut. I had been looking at audis and infinitis and both had a beautiful chestnut brown. When I began considering the MKC for real (I had been car shopping-test driving 6 + months) I knew I had to have hazelnut. I searched within 100 miles of where I live) and I'm right outside NYC. Tons of Lincoln and ford dealers, so very few with hazelnut interior, particularly loaded with all the options I wanted and color.
Because I could not wait to order my car I ended up having to give up 20 inch wheels (and second color choice) just to have hazelnut interior because I could not compromise :smile I liked it so much (particularly over the other color combos). It was the only one with hazelnut and all the other options. The black label brown colors are beautiful too. Like you I am looking for something a little different from my usual black.
I was disappointed the mats are black, was hoping for brown to match/compliment. I ordered some basic winter mats from loyds in brown but am dissatisfied because on my driver side where my foot rests the "color" is rubbing off. I don't recommend. They make beautiful brown custom MKC carpeted mats from loyds but they are $$$ the cargo mat alone is $200. Waiting to see if I'm keeping my car before investing $500 in mats...
Can't believe the hazelnut interior color is so restricted to the exterior colors (more so than 2015) on the new 2016s coming out. I think if you want hazelnut you can only get black, white, or silver exterior.