Because it is.

This was a big seller on Skymall.

colder climate: warm feet

We have a cushioned mat that goes under the toilet similar to this, though ours is mainly in front of the toilet, where this seems to go unnecessarily around the back. It gets thrown in the washer at the same time we throw the shower mat thingy in, the on you step on post shower.

I get that with an all female household it doesnt have much of a chance for pee splashback unless someone decides to be real fun and creative but it still seems disgusting.

Or a household where everyone sits independent of their gender. I got a dick and always sit, only time I don't is if I'm at a bar and the line for the actual toilet is too long and the urinal has less of a line.
I'm not sayjng this to defend toilet rugs, just to be clear. They're disgusting no matter.