Before he was introduced, I got the impression LE was an omnipotent demon who also happened to be extremely clever, what with how he works through proxies all the time and is never seen. He had an invisible hand and made stuff work in his favor without his direct involvement.
Nope. Laserbeamz out of his mouth. Kills dead people. Just about the least subtle thing anyone could ever do.
Why did Hussie build him up as some sort of spacetime pimp mastermind, and then do this?
My understanding is that Doc Scratch was the strategist. LE, on the other hand, is a master tactician - he seems to be actually quite good at comic up with tricks to bludgeon the spirit of the rules into submission with the letter, but if Vriska's opinion is accurate, he's not that good at working those tricks into the big picture, instead counting on them to win through sheer force of breaking the game. Right now, he's trying to tie up loose ends as quickly as possible - a reasonable thing to do, though he might not have anticipated the consequences or might simply think they're irrelevant since he can still kill anything he finds.
And, of course, there's always the possibility that giving definition and structure to the furthest ring will make it easier to find Calliope, who is hiding in a dream bubble somewhere and could well have been making use of the formlessness of space there as one of (presumably many) defenses. LE might actually find this to be crucial, rather than a side effect. This would, of course, undermine my first paragraph fairly heavily, but meh.