Flickr doesn't automatically owe any user the right to store their images in perpetuity, (over and above what their terms and conditions stipulate from time to time). I can see why they've made this shift.
Their free account holders have uploaded an immense number of meaningful images since the site was launched—but these accounts have also become a dumping ground for a massive amount of explicit images that are both banal, and of extremely low technical and aesthetic quality. The site has some truly dark corners I've unwittingly stumbled into at times, after inspecting the favourites of members who have followed me or faved my own images. For clarity, I'm not a prude, I appreciate a well executed black & white nude as much as the next guy: but innumerable explicit images uploaded to the site by free account holders are not only mediocre, they have been scraped from third party sites complete with watermarks and are not even the IP of the uploader. The new policies will be a form of laxative for Flickr, by cleansing it of much of this offending content littering their free accounts. I'm good with that (and as I still have under 900 images, I'm presently, only a free account holder, myself). If, as a consequence of this, some members formerly able to do so without charge, now have to pony up for the ability to upload their valued images of their next door neighbours servicing their wives, (or themselves, or their sisters, for that matter), well, I can't recall any nation's constitution inferring the right to engage in online exhibitionism free of charge. They can suck it, as far as I'm concerned (and god knows, they like to).
What also bothers me, however is the preponderance of second life screen shots that have infested the site in the last year or two. A veritable torrent of vacuous, vacant-eyed avatars mis-described as "photography", rather than digital "artwork". (If this comes across as intolerant and somewhat judgy, well, I don't really apologise for that—it does absolutely nothing for me.) It's in plague proportions, but apparently welcomed by site management, from what I have read in some help forum discussions. I assume the pro subscriptions connected to the content are what they find most attractive.
Lastly, few people with a genuine interest in history, or the history of photography, would willingly want historically or culturally significant images to be wiped from the web simply because, for example, the uploader is deceased and unable to renew a pro subscription, or has a free account in excess of 1000 images. This is a genuine concern, surely? Some type of submission process to safeguard, or "set aside" such images (or even, accounts) from deletion would be welcomed by me.