The only reason it is not a big deal is because it is in the back end but I doubt that it would be very appealing to any end-user eyes. What I mean to say is "What's the point?". From what I can see all it does is making the admincp unappealing to the eyes which in and of itself is not a big deal as only admins will see it but honestly why did it change? There was no point in changing it was there? If there was then maybe I am missing something and if so please tell me but until then I do not see why it has to look like something is missing/broken.
But it looks fine, the sidebar does not. It is extremely minor but it is annoying to see the sidebar look like that as it feels like something is missing.