Besides, respecting their existence is not what we, as metalheads, care about, and I would go so far as to say that that point is pretty irrelevant here. As consumers of music, we care more about the bands' music than about them as existing human beings. Respecting the existence of a band (for their influence, ties to other bands, or some other factor) is different from respecting the band for producing music which cannot be annulled by personal bias simply because it encompasses everything a band in a certain style (the fans of which are being directly addressed in the question; hence, metal in this case) should do.