opinions on free period and free the nip

I don't understand this I don't get why feminist go bra free or pad free or tampon free and stuff like that? First of all I wear pads knowing it's comfy for me and I wear pads so it doesn't start to stain my legs and smell even worse i just don't get why any one would do that this is my opinion what's yours?  I also understand that women don't like to wear bras but showing it in public?