I also have feet I've never used. What bothers me the most is all the stitches on my machine I've never used.
It seems the manufacturers put a lot of stitches on a machine that doesn't get used.
I've often wondered why? Just to up the cost?
Sewing machines should be more 'generalized', only having stitches, etc. for more specific sewing needs.
I guess its easier to put everything on a machine, so whoever buys the machne its versatile to all types of sewing. (?)