I think the Reddit execs see other aggregators just ripping off things that were popular on Reddit[0] and thinking that they are missing out on a potential revenue source.

Their user base seems to really dislike this move[1], but it seems to be more of an expansion to get users that don't normally use Reddit. I imagine users of Upvoted will be people that would normally use Buzzfeed or 9gag, probably largely disjoint from the actual Reddit community.

[0] https://www.reddit.com/r/SubredditSimMeta/comments/3fnkni/9g...

[1] 45% upvoted at time of posting: https://www.reddit.com/r/blog/comments/3npxm4/introducing_up...