Children who hate sport might not hate it so much if they find one they enjoy, that's the reason for giving them an opportunity to try out more sports that they might not routenely do. Although I can only really speak for the way our school has done days like this, they are the sort that are aimed at non sporty children.
Seakelp, I find your response very odd. Days like this aren't a reward for children whose parents can't be bothered to feed them properly or give them an opportunity to excercise.
I think that's quite a horrible thing to imply, that every child that is not interested in sport is brought up badly. My ds is one of the non sporty children when it comes to PE lessons, but he loves swimming, chess, reading, piano, cubs activites, lots of things. But if schools get funding to promote sport (don't know about your school, but that's what it was with ours) then it would be money better spent on encouraging those who don't show much interest in sport to hopefully find something they enjoy.
It really is like them being given funding to promote reading, then spending it on the ones who are brilliant at it and have access to lots of books at home. Or promoting musical instruments to children who already play three.
I can understand you wanting your dd to have her chance to show what she is good at and do something she will enjoy, I really do. But if you fell that teh school isn't giving her that opportunity then I think that is a separate issue to what they are doing for non sporty children. You should talk to them about what they are going to provide for her, or arrange something out of school. But also remember that they will have PE lessons every week, which of course you don't get to watch, but where it is likely that your dd does very well, and gets praised for that.
There are lots of examples around of pc gone mad, but I don't think a child that is good at running not being automatically placed in sports day running race, or being allowed to go to an event specifically intended for non sporty children is one of them.
Do you know what she did/will be doing at this year's sports day?