My improvements would be:
Two dances (one Latin one ballroom) each episode so everyone dies the same and you can compare.
Props allowed once per couple per series.
No extra dancers.
Appropriate costumes - only dress up on Halloween.
Pros choose the music again. Apparently it's chosen by the producers now and they clearly have no idea!
Change the judges. Not Arlene - she is cringewoethy in how she drools over men. Karen Hardy would be fantastic.
Backstory reduction. VTs concentrate on the dancing.
Love Claude. Hate the enforced silliness. Get rid of the weekly "joke" and reduce the idiocy.
No more themed weeks (except Halloween!)
Stop pretending it's filmed over two days. Just why?!
It's a start.