To wax or not to wax, that is the question...and I do both, depending on the foot.
I generally prefer trimmed feet. On most forms, it looks better, reduces the overall weight of the pot and provides a cleaner overall aesthetic. Because my trimmed feet have contours that can capture glaze, I find that the time it takes to wax the foot is more than made up in the time it would take to get the glaze out of all the nooks and crannies in the clean up...but I have exceptions.
Also, there is a real advantage to mixing Alumina Hydrate with the wax you use for the bottom of pots - especailly in public studios where the shelves tend to take a beating. It provides an extra layer of refactory (does not melt) material that keeps your pot from sticking to the kiln shelf.
That said, my mugs and some of my sculptural work have flat bottoms and these I do not wax. Instead I have modified a really cool process I learned about 10 years ago when visiting my husband's family in Hódmezővásárhely, Hungary. Hódmezővásárhely, btw, roughly translates to "beaver field/meadow marketplace," I think. It is a beautiful small town in south east Hungary and home to my husband's Aunt and her family...but I digress. Back to glazing.
Knowing that I made pottery, my in-laws took me to a local pottery that made Hungarian blue folk pottery. When cleaning up the bottom of a glazed pot, they dipped the whole piece in glaze then immediately rubbed the bottom several times over what looked to be a canvas covered sponge. When I got back to my studio, I tried this technique with a regular, large cellulose sponge that was very saturated with water and it worked wonderfully. The process no only completely cleans the bottom of the pot, it also feathers the bottom 1/8-1/4 inch of the glaze which helps prevent the glaze from running. You can do maybe 3-4 pots before you have to rinse the sponge.
So to wax or not to wax? Both.