Copyright is supposed to exist for a limited time to "promote the Progress of Science and useful Arts." The current 100 year plus regime is effectively forever and not in line with the original constitutional purpose. With reasonable copyright timeframes, at some point all copyright will expire and then everything will be legal. The notion that an artist is entitled to extract money from each eyeball or ear that encounters the work until the heat death of the universe is unethical.
I agree with you, but that's not what's happening in this conversation. Nor are any of these services a historical archive, they are ongoing catalogues and your subscription funds new shows, as well as servicing cost.
And let's not feign ignorance by saying the overwhelming vast majority of things being watched are exactly that new content, not 30 year old reruns of Frasier.
EDIT: I apologize, only ~2 seasons of Frasier would extend past copyright. It started airing 1993.
What does that have to do with streaming services?
Probably 80% of what is watched is from the last year, a lot of it from the last month. Most of the rest is from the past couple decades. The original US copyright law of 1790 allowed for 28 years.
I mean, I agree current copyright is too long. It's just not that relevant to streaming. Not a lot of people are looking to watch old episodes of Knight Rider for free. (Those who are, I salute you.)
Given that the law is broken and the entertainment industry is generally responsible for that, it seems reasonable enough to decide you don't want to give them money that they will use against you (perhaps making exceptions for indie groups). Once you've made that decision, piracy (at least downloading) becomes amoral. Whether you watch the stuff has no effect on anyone else (personally I don't, but more because I'm not interested).