Streaming is downloading. The information is on your PC; you should have the right to do with it as you please forever.
It is akin to the marijuana legalization movement in many ways - pot was always illegal, so it should always be illegal, and to question why it is illegal is to be unreasonable. Debate about sentencing, classification, possible medical use - possibly reasonable, but to question the fundamentals starts drawing on cultural and emotional ire and identity that starts breaking down reasonable debate.
Copyright to many works much the same way - especially when no new works have entered the public domain in the lifetime of the vast majority of the populace - it has always been there, thus even if you debate duration you assume it must remain because to question why it exists in the first place is, again, to be unreasonable.
But the fact remains that copyright is the law today, and encouraging users to break that law is apparently a consequence of what Google did. It's not unreasonable to debate the actual legal situation, not the legal situation that people who don't like copyright would prefer to exist.
No they really are not, and have never been
Copyright, historically, is a tool for Information Gatekeeping, censorship, and profiteering. Not one of benfiting the Creators of content
See the Talk on the History of Copyright https://www.youtube.com/watch?v=mhBpI13dxkI
We see this every day in the modern era where copyright is used to censor critics, prevent research (especially security research), and prevents more content from being created by locking up ideas for over a century
Copyright is a Negative for Society, and for Creators
The idea that as soon as data hits your computer it's yours to do whatever you like with doesn't really hold up to any legal analysis.
And that idea was solidly cemented back in the days when VCRs were common - you had a right to record anything and watch it again whenever, wherever you liked.
What you never had the right to do, even with a VCR, was something like borrowing a movie from your local video rental store, paying a lower rental price rather than a full purchase price for it, and then copying that movie so you could keep it after you returned the original cassette.
Where is this legal? I'm quite sure it would have been an explicit breach of the membership conditions for every video rental store I ever belonged to in the UK, for example.