The FX 5200 was the base card and Apple used it in base models, it had some advantages, like it could decode MPEG2 HD content in hardware.
Like it or not the 12" Powerbook was a base model, we wish it had come with at least a Radeon 9600, but it just didn't.
More of a higher end market for compact Mac laptops today, just wasn't the case back then, if you wanted GFX performance you had to step up to the larger screens/bigger laptops.