Waiting until every world has won to implement a delivery method for all characters on all worlds is much easier than implementing a delivery method for selective worlds. I'm sure that at no point did they plan for the possibility of certain worlds not winning.
Same thing as FFXI in 2003 when the outpost teleports were awarded to worlds who had defeated their Twinkling Treant. Of course they wouldn't let a world go without that feature.
I don't really see the point of a lottery where everyone wins, but hey, I can't complain about winning something!
Its called PR. The game has been out roughly a month, they needed foot traffic at TGS to keep hype, and by causation, sales up.