The comment of:
“” but if you look into the story lines”
True, but by that standard much of Tanakh would be problematic.”
has implications that border on apostasy, CH”V.
And how dare anyone compare our holy Tanach to the depravity of the secular world?
Looking into the story lines of an opera, by your own admission, indicates various problems that make it unsuitable for consumption by G-d-fearing Jews. You mitigate that by positing that Tanach has similar issues, CH”V.
In this regard, the key difference between opera and, lihavdil ribei rivavos havdalos, our holy Torah, even assuming the stories are somewhat similar, is that if Hashem chose to put the story of, say, pilegesh biGiv’ah in the holy Torah, then he intended at least someone(s) to intentionally sit down and study it learn something from it, perhaps not a 10 year old child, but certainly some people at some point in their live(s). And, equally important, even *if*/when there were aveiros committed in some of the stories, there is no tumah in appropriately *learning* about it, as Hashem and His Torah are kulo kodesh. There is certainly no such guarantee about much else on this earth, and as you yourself admitted, certainly not on an opera performance.
Even if you might find one or more positive lessons to learn from an opera show, which is quite possible, this does not permit one to trample the other issurim to do so. So the holy Tanach (of all things!) cannot be used to justify immorality nor CH”V to suggest that any immorality is found in appropriate learning of the holy Tanach which is the far worse of the two implications, imho.