Everyone who saw a Star Wars film wanted one.
It was probably one of the first things to pop in mind of anyone who imagined a motion control based sword game back when the Nintendo Revolution was announced. Back in 2006.
And then it turned out Wii motion controls weren't that precise or 1:1.
Then Motion Plus gave us Wii Sports Kendo, which while an improvement, was hardly worth buying even a $20 attachment. At that point, I think the only reason we didn't see a Lucas Arts lightsaber duel game is because they had just released one with regular Wii controls. Bad timing.
For me personally, the closest thing we got was No More Heroes even though it used an on screen cue for directional slashes having nothing to do with 1:1 controls. Still a load of fun.
Lucas Arts released that lightsaber duel game, but that didn't seem to even register a ripple when it was announced no M+ due to being deep into development before the M+ dev kits were available.
Personally, I think I'd rather play a lightsaber game on the PS3 now with the Arc controller. Better motion control system, better graphics, higher resolution all mean no reason to wait for something like that to come out for M+ Wii or even buy it on the Wii if such a game was released on both platforms.