Because I don't have enough time/budget to maintain 2 different interfaces, and the game needs a design that works for both desktop and mobile in order to prepare for the upcoming mobile app.  This means the old one is no longer supported or receiving bug fixes, and will eventually be phased out entirely as we focus on the new design.

I agree that it's not winning any beauty contests, although the old one wasn't either.  Unplayable though?  That seems at least a little hyperbolic.

Specific suggestions are welcome.  What did you like about the old one that the new one doesn't have?  The players' input in the feedback and ideas forums have been very useful in improving the new interface.  It's leaps better today than it was a month ago thanks to players providing specifics.

You guys are of course welcome to switch back to the old, as Bandito mentioned and as I assume Lightguns is doing.  Just to be clear though, our usage stats show that most players in fact do not do this.  It doesn't make sense for me to focus on features that only a minority of players are using.

In short: you are welcome to continue enjoying it for now, but it *will* go away eventually.  Our time is better used focusing on improving the new design.

The ongoing work plan is here if you're interested: https://trello.com/b/gNAr9gke/tasks

Feedback/Ideas are welcome in their respective forums.