Because it kicks ass, lol. With the boots and jetpack I can actually fly just as fast as I would with a Swiftwolf's (which I can't yet make), and the diamond pants is just for armor really. The sword, well... It's flashy when turned on and does a huge amount of damage!
And the goggles they speak for themselves I think (I mean.. LOOK AT THEM!).
You could use Dropbox to play on your account on different computers by doing this - while still being able to play on your worlds.
If you don't share the .jar with anyone else it wouldn't be illegal.
There is really just ONE thing that bugs me.
When I had to reset my password after you migrated our users over here, it seems my age is suddenly 112. FYI, I am not that old - it's 93 years older than I really am. Rofl.