I have two theories behind this.

First, to reduce that cost of “free” accounts that is signing up. They have talk in the past the massive issue all that SP was and how it would be an issue down the road for Steemit growth. For them to just grow to the size of reddit would have been many billions in value worth of SP to do so.

Second, defang those abusing the free account sign in. Spammers who start out now have massive bandwidth issues if all they want do is spam. Those who are getting around the “only” one free account per person protocols/protections now have less power. I’ve wittiness maybe 500+ botters get their upvoting powers reduce massively due to the changes.

So, while we all love to have more SP and that free stuff will be missed. It is going to help grow Steemit at a reasonable price. People looking to abuse the system now have much less power via free route.