I think realistically with 200 some base models and about 100+ parameters that can be tweaked for each model, any given tone under the sun is there. I think its unlikely that there is some amp out there that sounds so one of a kind only by specifically modeling it can the tone be realized.
That said, I think power of suggestion and playing with our eyes, instead of our ears, goes a long way towards users overall enjoyment.
Its just like how the Gilmour fans on the forum are always asking for a specific version of a specific model of fuzz. No denying the Axe can dead on nail Gilmour's tone; just go see Brit Floyd for proof, BUT there is that certain mental affirmation that comes from selecting, say a "rams head muff" from a list, even if the tone can otherwise be recreated sonically.
Its that affirmation that we are doing it right, that we are using a specific model which was used by our guitar hero, and not only can that make us perceive it to sound better, but its also kind of cool, especially when an artistic own specific amp was the one used for the model, right ?
I mean take Keith Urban for example. Am I ever going to be able to play his actual amp ? Doubtful, but in my Axe I can have a very exacting model of his specific amp. Is it realistically going to give me a tone I couldn't otherwise tweak and come up with ? Probably not, but its still cool.