A brief consideration of opera costumes and updating

I posted the following as a comment to a YouTube video about historical costume accuracy in movies, television, and theatre:

From Maria Stuarda at the Met
The costumes were highly praised,
but the confrontation scene only
happened in the novel. 

This was fascinating. You make me think of all the inaccurate opera productions--at every budget level--I have seen. A very low-budget organization can be forgiven for using what they have in their costume shop rather than going to the expense of making or renting a more accurate costume.  But really? Donna Elvira (Don Giovanni, late 18th century) dressed like Lady Bracknell (The Importance of Being Earnest, 1900)?  

Another questionable practice in the opera world is updating the historical era of the story, when in so many cases the relationships in the story only work in the original time period of the story. OK, Parsifal in a post-apocalyptic world can work because the story is sort of timeless. The Marriage of Figaro in Trump Tower--the infamous Peter Sellars production from the 1980s--or Elixir of Love that looks like the movie Baghdad Cafe? Although I have seen it work, more often than not the incorrect detail of the less remote historical period they have chosen (no, not every opera works with Jackie  O. fashions!) over the historical period in the original story is more distracting than clarifying. True, the original libretti and/or the literary works they were based on are often very inaccurate in portrayals of historical period or events, but this just adds insult to injury.

Your thoughts?