While it's correct that you won't get the items, it's still not completely useless.
This once was a bug (I've had it myself on a testserver randomly, years ago), but back then a click on the button would make your mojo count go one less, so -2, -3 and so on. Back then you also got the items - now this has been fixed, and your mojo count sticks at -1 (until you collect a mojo glitter on the water).
Anyways, it's still interesting because it can be used to calculate the probability for each item. E.g. how many mojos do you need in average to get a mojo deck? How many for one Cancer map?