SilverWook said:

Before people start really flying off the handle, try thinking in universe for a moment. Design flaws aside, the Death Star is an effective weapon for scaring planets into submission. And flaws can be fixed.

The know how to make one doesn't magically go away. It's like a nuclear weapon, once the genie is out of the bottle, somebody sooner or later is going to want to build one.

And how do we know this one belongs to the Empire? They aren't the only ones with a copy of the original technical readouts. ;)

Also what is up with Leia's hair? I'm getting a Mom from Futurama vibe here.

I can't agree more with this. If weapons technology that can destroy entire planets exists it would seems stupid to not follow up on and improve that technology. It would be like if after WWII we decided that Atom bomb was old hat and never developed nuclear weapon technology any further. While It may seems lazy from a storytelling perspective at first sight, we don't know how exactly the weapon will factor into the film, that plot structure could be quite different.