We're not some bunch of evil dictators. We care about our community - ALL of our community. We made this change knowing it would not be popular with everyone... but very few things are. And sometimes difficult decisions have to be made to advance the site forward, as we are continually striving to do.
As has been stated above; vDip has a lot of choices when creating games, and that isn't something we really want to add. We try to make for a simple and cleaner experience here, focusing mainly on Classic and competitive Diplomacy. Lots of different scoring systems does not really tie into this.
Jamie above listed the main opposition to this change... but that's exactly the point. The opposition *can* be listed, making them a vocal minority of what is already a vocal minority (the forum). Now, this does not mean that we don't value your opinions, but it does mean that we need to look at the silent and vast majority of users who never go near the forums. There are a few key metrics we can look at to see how they have reacted to these changes, and we will continue to monitor feedback as well. So once SoS and Unranked games start ending and people are used to them and understand them, we can compare metrics such as unique users in games, games created, the ratios between WTA:Other games, and many other things; and only then will we have a clear idea of how the *whole* community has reacted to this change.
ATC stated in the original post that this change might not be permanent, but we're not ending a trial after less than a week. Have some patience, give the others a try, and see what you think of them. Personally, I have never enjoyed DSS/WTA very much, because I find people group against a solo without thinking of themselves far too easily, and very much look forward to playing some SoS games in the New Year to see whether that changes when SC count matters. Unranked games allow for even more possibilities; and Valis' upcoming Local Tournament allows you to experience a rank-based scoring system in Carnage, too.