As far as catchlights 'making the eyes come alive', especially in a larger scale, doesn't it make more sense to mimic the appearance of a wet eyeball if you've used metallic paint, have a glossy finish on leather and so forth; after all don't most of us paint this way, so why treat the eyeball differently?
Again, if you've painted an entire bust matt then you should be replicating the effect of light entirely with painted illusions (something at least partway toward zenithal/overhead lighting) so then a catchlight is appropriate to the handling. Mixing this style up with the standard way of painting doesn't really make sense though - why a specular highlight on the eyes but not on the corner of a buckle, on a gemstone, on the top of a helm, the edge of a blade, the toe of a polished boot etc?
One of the things that looks funny about catchlights on something in the round is that when you rotate your viewpoint the illusion of reality is lost as the white dot is stationary; this is also true to some extent of zenithal/overhead lighting itself. Once you stop rotating the figure or moving your viewpoint the effect comes into its own again, which is why this style can look so effective in photos.
Einion