So in summary Flickr is giving free users hosting for 1000 photos of unlimited quality vs. 1TB of free storage to refocus on photography vs. data mining for advertising. Makes sense to me.
When you look at the comments on Reddit, you can see that unfortunately it does not make sense for many people who put free as their first priority, versus privacy/sustainability/data concerns.
Very brave for Flickr to make this move and face all those critics, even if this is for the best on the long term.
I would be very careful about drawing any sort of general conclusion from self-selected Reddit users. The most entitled people are going to complain loudly but I'd be skeptical that they're a substantial percentage of the people who contribute any value to Flickr.
While they may not be a good foundation to build upon, they are good marketers. Just a roundabout way of saying adoption begets adoption and barriers are the opposite (though sometimes the trade-off is worth it as may be the case here).
I would wager Flickr stopped growing significantly a while ago, and therefore doesn't benefit from any marketing that people with free accounts might do for them.
And as the saying goes in creative industries: you can't eat "exposure." The only way to make money is the charge money, and it's generally worth it even if it means pissing off people who expect stuff for free.
Heck I bet this change will drive up awareness of Flickr. I can't even remember what I have there, but now I'm going to look up my creds and log in to find out.