I think that too, if only they had made it a "Night sky paintbrush!" or if they had to use Eventide make it an animated brush that literally changes as they NST clock ticks - so in the afternoon the pet is the afternoon sky, in the evening the sun's setting, at night it's all dark and starry *_* Actually, that would just be really cool, if they started making sort of animated paint brush colors - so the faeries wings fluttered, the patterns on the disco pets swirl around and around, etc. I've also thought it a good idea if they animated the Neopets even just a bit, so they blink sometimes and move around a bit, their ears twitch or their tails flick. It would be a lot of work I suppose but worth it, I think, rather than the pets staying static - gorgeous as many are.
Oh, and if they animated when the pets were starving or sad! If their crying or their happiness was animated, or their being sick. It wouldn't have to be a huge animation but it would make things so much more interesting on neopets, at least I think so.