I've had two BMW's with red and black interiors, they look great. I'm not a fan of "Solid" Red but mix them up and I think "Awesome" ..and don't ever spill Windex on them, the colour runs and stains other things (like pants, dresses etc)
I'm sure trends and tastes change as others have noted. For me I started with an all black interior with black everything seats, doors, dash, carpets, hood, etc. and that was the German way of a few years ago - just too drab and dark.
I think the red seats and door inserts just lift the whole interior and take it to the next level
See how well the red works against grey paint and black in these shots:
Think back in 03/04 red interior with silver outside was not a popular choice .... in the launch brochure that I've got a copy of there is not a single photo of a Z4 with a dream red interior.