For me, it all stems from opera's status as a hybrid art form. There's
an irresolvable tension between its various elements, as evidenced by
the 400 year long dispute about the relative importance of words and
music and theatrical production, along with the periodic efforts of
artists--Gluck, Wagner, etc.--to reform what they see as the excesses
and imbalances of the previous generation. The advent of opera on film
and video has only further complicated the issue.
I think the best course is to embrace this inescapable tension, along
with the differing viewpoints it engenders. I'm not claiming that any
one approach is correct. I'm just suggesting that the mixed nature of
the art form almost guarantees widely divergent perspectives.