Ok, because I agree EXACTLY with what you said, and I am hoping that you agree with me, right?
Because right now, I find exactly what you describe: there are, to stick with my main example, about one GAJILLION versions of a "Fender Precision Bass" currently on Equipboard. So I can't search for a p-bass and find any but a handful of Fender p-bass playing artists.
My only caveat to your suggestion is that instead of a text-only "information box", that where applicable, SEARCHABLE SUB-FIELDS can be added to a given instrument/amp/whatever. And where applicable (color, neck material, etc.), it would even allow for a more precise picture! This way, if I want to search for every artist that uses a "fender, p-bass, black, maple fretboard", I could! Meanwhile, we could still have sub-fields, where appropriate, for things like country of origin and year of manufacture (both of which are big deals for collectible things like guitars and amps) that wouldn't change the pic, but could even be searchable--I mean why the heck not?
On a side note, all I see is the "review" for an instrument--I don't see that there is even this "information box" that you are talking about, but you make it sound like there is already such a thing? Am I missing it somewhere? Because I think that this would be an EXCELLENT idea, IN ADDITION to the sub-fields, where UNIQUE details could be added (stickers on a guitar, special mods to an amp, etc.) for an artist's gear.