On the After Effects List, some of the AE team shared background on the Cartoon filter (see the Chris Meyer highlight movie), which has been been seen as symbolic of a lack of development focus by Adobe HQ.
Lost in the shuffle is that Cartoon is one of 3 the new GPU-accelerated effects; the others are Turbulent Noise (an improved version of Fractal Noise, but without looping) and Bilateral Blur (like a fast Smart Blur). Anyway here's the story:
The Cartoon effect was written using the same foundational technology that underlies Pixel Bender. So, rather than thinking about the time spent on the Cartoon effect as being just spent on the Cartoon effect, think of it as time spent by our best people on implementing, testing, and improving a platform on which all sorts of fast and flexible effects are being built.
If you want After Effects to use your GPU effectively and provide an easy way for users to create effects, then you should be happy that time was spent on the Cartoon effect.
For the whole back-story, it's what Todd said, plus this detail: Holger Winnemöller was hired into the research group at Adobe after doing his PhD thesis on real-time video abstraction.
Siggraph paper: http://videoabstraction.net/papers/videoabstraction.pdf
Demo movie: http://videoabstraction.net/movie.php?size=large
BTW, the technically superior Red Giant ToonIt costs $379. Upgrade to AE CS4: $299.