I think BL should be a tier. When people think of UU they want to play with altaria and nidoking type pokmeon not blissey snorlax and latias.
Yeah, I've heard a lot of people talking about making some sort of new tier to help organize things. After all, the way UU is now, old UU favorites like Sceptile and Ambipom can't shine without dropping to NU (which we don't have yet, I know, but we will...eventually). When that happens, old NU veterans won't be able to shine anywhere. However, I'm not so sure about making BL a playable tier. A friend of mine came up with an idea of creating something like "Lower OU" and "Upper OU", but I guess making BL a tier would keep us from having to invent new terms.
Long story short, and I said this before, I really hate what's happened to UU...