Firstly welcome aboard, and thanks for reviving some fond memories.
I too have a soft spot for the old triples, I had a Suzi 550GT with the 'Ram-Air' system which stopped the middle pot cooking, and a superb 750 'Kettle' which was suprisingly chuckable for such a heavy old bus.
But to answer your question I don't thionk they've been ignored, it's more the scarcity of them that stops people from cafe'ing them. Even the later bikes are now 30 years old and as such getting quite rare.