A common thought at the time was that Digg made the changes to increase its Page View metric. This thought is based on the fact that links inside a users profile page were changed in such a way as to no longer allow "blind digging" of a user's submissions.
Many people focused on the "extra" click now required to get to a story. With the "Digg this" button removed from the profile page (and the story synopsis) anyone who went to your user profile page to see what you were up to would have to click on each story (going to the digg story page) before they could digg it or even get the story synopsis. This "extra click" methodology was seen by many top diggers as a way for Digg to quickly increase its Page View metric.
If you look at the old Digg profile page you will see that you can quickly interact with a story without ever going to the story page on Digg. You need never go anywhere but a user's profile page to find content on Digg.
The old Digg profile page looks a lot like all of the category pages on Digg. If you go to any non-profile page on Digg you will see content presented in the same manner as was once done on the user profile pages. It is only the profile pages that have been redesigned in such a way as to increase Page Views.
This tells me that this was not done to increase Page Views even though it likely will. There is a bigger change at work here and something that many people did not catch on to.
As you can see with the new profile pages there is no ability to digg, bury, comment or even see the actual content until you click the link and go to the story page on Digg.
By changing the user profile pages so that they link to the Digg story and not directly to the story content (off of Digg), Digg has removed one of the biggest reasons SEO types spam Digg: BACK LINKS.
In the past every person who dugg a story would generate a back link in their user profile page, sometimes several back links. Every digg and comment created a new link in the profile page. If a story received 1,051 diggs and 500 comments that story would receive in excess of 1,551 back links from Digg. I say excess because you still get multiple back links from Digg due to the various category, sub-category and other areas a story can appear on Digg.
By removing the back links in the user profile pages Digg has both increased potential Page Views (you need to click twice to get to content from a profile page) and decreased the amount of back links that Digg provides. There is now no reason for a spammer to submit crap to Digg in the hopes of getting some back links.
Why? Because when a story gets buried it provides no more links, anywhere on Digg!
Sploggers will still try to game Digg for traffic, they just can't game it for SEO anymore. I wonder if the change at Digg had something to do with Page Rank dropping on so many Tech and News sites?