I had a lot more respect for this before I realized it was an April Fools joke. Why limit such creativity to one day in April that's just awash in the inane?
I don't think anyone here truly thinks that there's a time restriction on creativity. April Fool's day just gives us all an excuse to be a little silly, and collectively indulge in some light humour.
If anything, the day acts as a sort of prompt for this kind of creative work. It doesn't limit creativity, stuffing it into a once-a-year box. Instead, it encourages more creative projects that otherwise wouldn't occur.
Haha, I was very enthusiastic, finally a fun game I'd like to play. Then was disappointed when I realized it was an April Fool's joke. It's really funny though. Props for Atlassian.
(Despite just being a good joke) there's something to be said about the link between success and product familiarity/likeness. The "success" being that it got all of our attention (300+ votes on HN). It's more than just a cheap trick; companies copy ("learn from") each other's ideas and UI layouts all the time.