Other than by the development effort and $$$ (some of them ours) being diverted into such sideshows and away from the DDA and what the game that we backed with our money was supposed to be. But yeah, other than that no reason to be annoyed at all.
Well backing a project does not entitle you to anything. You are not an owner or an investor. You may be a very nice person pledging for something, period. That dues not give you the right of "I spent more money make the game I WANT before what others want".
Besides, assuming arguendo that money is a valid point, well arena thingy might end up bringing in more players, making the devs able to further their vision more with it than without it. So this is also in the backers' interest.