I didn’t get the appeal either, until one day, I was riding one of my favorite dildos, a large manbearpig in soft. Picture attached, it’s the pink curly one.

So anyways, I’m kneeling on a cushion, with the base on the cushion between my legs down by my feet, moving myself up and down to fuck myself with it. I pull off of it (I don’t remember why but probably to add some more lube) and this giant slimy floppy dick, now warmed by my body heat, flops over, right onto the sole of my foot, and like, damn, now I get it. I don’t go looking for foot porn or anything but I’d probably enjoy giving someone a footjob. Also, a dom once made me suck his toes, but that was hot to me cause of the submission, not the feet. Ymmv.