Think of it this way:
When you pluck the string you put in a limited amount of power. You use that power to move the bridge. Moving the bridge involves accelerating it from a stop, and then stopping (decellerating) it again so that you can acclerate it the other direction. High frequency response is all about acceleration. You know that if you want a lot of acceleration in a car, and the horsepower is limited, you need to keep the weight down. Same with guitar tops: if you want high frequency response you need to keep the weight down.
Of course, the top weighs a lot more than the bridge: three or four times as much, at least. Still, the weight of the bridge has a lot to do with the frequency response becuse that's the first thing the string 'sees': a lighter bridge will generally be more 'treble balanced' than a heavy one.
There's a price. One of the main 'jobs' of the bridge is to tell the string how long it is. 'Ideal' strings, ones that make perfectly harmonic sounds, have to have the ends fixed, immobile. Of course, if the bridge and top on your guitar didn't move at all you'd never hear it, so you can't have a 'perfect' systyem in that sense. You do have to provide enough stiffness and mass in the bridge to keep things under control, though. Too light a bridge will cause 'wolf' notes by feeding energy from the top back into the string. This can drive you wild.
IMO, and it's only my opinion, a thirty gram bridge on a classical guitar is too heavy, and a fifteen gram bridge is too light. I usually shoot for around 24 grams, more or less. It's hard to get that light with ebony, possible with Pau Ferro/morado, reasonably easy with Brazilian or Indian rosewood, and a piece of cake with walnut. It's hard to say what role the actual damping factor of the bridge material plays, but it probably doesn't hurt to pay some attention to that, too.
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