A long time ago I learned one of the golden rules of parenting: pick your battles. We can't have everything our way and neither can our kids, so we get choose what's worth fighting for and what isn't.
I decided to let my six-year-old have complete freedom when picking what to wear for playtime. She needs to wear a uniform to school, so outside of that she gets to choose. Truth be told, I also made that choice because I love watching her express who she is. She comes up with some unique outfits and I document it because it's just a phase.
Everything in life, but particularly parenting, is a phase. One day they love something and the next day they don't. I remember when my middle daughter was three years old and would only wear her bathing suit. Since we live in California that was okay, even though it was January. People kept asking me if she was on her way to swimming lessons. I responded, "no...we just dress like that."
No matter what phase our children are in we get to celebrate it. If they want to ride their bike all day every day, enjoy it and capture their joy. If they wear those Elsa faux Uggs everywhere even though you're in the middle of a heat wave, who cares. I love it! I cherish it! Because really, who other than a child would have enough inner confidence to not care at all what other people think of what they wear. And sadly, that's just a phase too.