My rule is for my guys that we are in pants unless I say otherwise. Occasionally we will have a light day - maybe just BP - where we get out a little earlier than normal and they can wear shorts. Other than that we are going all out in practice.
Coaches can wear whatever to practice. Normally I wear shorts and a pullover / hoodie for practice. My coaches will wear sweatpants. If what we wear affects how my guys play or respect the game then we have bigger issues. Now if somebody else wants to wear the uniform to practice that's fine. I have no problem with it because you do you.
I coached softball one year and wore khaki pants / shorts or gym shorts with a hoodie / pullover during games. It was without a doubt the weirdest feeling in the world. I didn't like it.