The feet are only there to be used on a non flamable patio or driveway when you don't have a table or a nest to help make the EGG sit level. You don't get feet with an XL so you got what you were supposed to get.
If you put the EGG in a table it needs to be sitting on a concrete paving stone and doesn't need the feet. We have one EGG in a table here at the store that is on the feet so we can show what you are not supposed to do.