CNET:

Don MacAskill, chief executive of SmugMug: “I’m sure we’ll lose some of those people. Fine. They’ll use Google Photos or they’ll pay us. Either is fine. They can’t continue to chew up huge amounts of storage with photos that don’t contribute to the community. We are no longer focused on everybody. We are focused on photographers and people who care about photography.”

I think this is the key to the way Flickr is looking at this. I understand that many people aren’t happy about the decision but, given the above, they feel it is the best decision for Flickr/SmugMug going forward. I still haven’t decided if I’ll switch to the “Pro” tier or not though.