That's absolutely terrible and I agree with you. Those days should be totally optional. Not every family is resourced to provide themed outfits and as you point out, not every kid welcomes participating in such.
I hated theme and spirit days when my kids were little. And guess what? Now that they are in high school not only do they still have spirit days, but their sports teams do team spirit on game days. Some days it's just "dress nice" but today was "black out" (meaning wear all/mostly black) but they pick others like pajama day and such. THEN the varsity football games and varsity basketball games also have themes (regardless if home or away) for their student spectator section so my kids have to find "costumes" to wear to those too!! Like construction worker or frat boy or pro team jersey, you name it. Whatever happened to wearing your school colors to cheer on your school?????
Mom to two amazing DDs ('07 & '09) and a fur baby.
Gluten free since Nov '11 after non-celiac gluten sensitive diagnosis. Have had great improvement or total elimination of: migraines, bloating/distention, heartburn, cystic acne, canker sores, bleeding gums, eczema on elbows, dry skin and scalp, muscle cramps, PMS, hair loss, heart palpitations, fatigue. I'm amazed.