Iota, I think that it depends on how easy your children are to manage in a car park. Mine are now fine, but when ds was 2 he was a complete liability and would run off given a split second.
Also they are now on booster seats, easy for me to belt them in. This wasn't the case when they were smaller.
I don't use these spaces either, but I recognise that some people do need them. The reason I get fed up with other people using them is the basic selfishness that it shows. They are saying, in effect, that their needs come first, regardless of anyone else. That is just plain bad manners in my book. And even worse these people will also take blue badge spots....indefensibile.
It isn't the probelms that these people cause that gets my goat, it is what their behaviour says about them, and our society.