Math
no, not everything was better in the past. Not everything is better now either.
However, I don't understand what is wrong with asking/expecting parents to be washed and dressed for parents evenings- to me, it shows a bit of respect to the teacher and that you value your child's education. What does it say about the importance of the parent's evening/school concert, or whatever it is you are attending, if you can't even be bothered to get dressed to see your child's teacher?
If I turned up to do a clinic unwashed (if you've had time to have a shower, then you get dressed after the shower, surely?), in my pyjama's and so on, I think the vast majority of my patients wouldn't be very happy (nor would my employer). I don't have to have a full face of make-up or have perfectly done hair, or be dressed in immaculate clothes- just clean, neat and tidy. For me, that is about respect for patients and actually, respecting myself too.
I like school uniform, I think it solves some problems and looks smart.
As I said previously, wearing pyjama's on a rare occasion on the school run when everything has gone wrong? While I haven't ever done it and would most likely find time to put on some clothes, it's not the end of the world. Anything more formal, and you should make the effort to at least be fully dressed IMHO.