One criticism that has always been attached to TV animation is the quality of the animation. "Limited" animation was just something TV had to do for economic reasons. That doesn't make it any better to watch specially when compared with old animation shorts. It's disheartening to see a fifty year old short beat the pants off of the animation today. Still a clever animator can certainly make a limitation work for him.
Craig McCracken is a very clever animator.
Using a very kid friendly color palette and a design that was like a series of kid drawn pictures; he perfectly captures the kid-centric world of the Powerpuff girls. Here kids not only matter, they save the world. Well Blossom, Buttercup, and Bubbles do, but kids can live through their adventures. Add the world's most perfect dad and it's the perfect kid fantasy.
Thankfully McCracken didn't stop there. He knew that to be a really good toon people have to care about the heroes. The animation may be limited but the writing never was. The ups and downs between the sisters were always well written and universal. If you had a brother or sister you know all about the occassional rivalries, jealousies, and misunderstandings that crop up even in the very best relationships.
McCracken also realized that heroes are as defined by their villains as they are by their costumes. The Powerpuff girl's rogue gallery is wonderfully hip, funny, and the villains that you ALMOST wish would win. The best would either have to be the surly monkey genius Mojo Jojo who murders the English language worse than Yoda, or the very disturbing devil figure known only as . . . HIM.
Add to the mix some sly humor that even adults can enjoy and you have something very special indeed. I personally love music the show has inspired from the girl's own world saving song:
and even Devo!