When multiple shapes are selected and use the split into grid tool, instead of split each individual shapes it creats a big box to contain all the shapes and split the big box instead. Who would want that? If I select multiple shape obviously I want to split them individually. If I want to split a big box I'll take a second to create a big box first instead of ruining my delicate little shapes.

Also, it'd be appreciated if it can split more than just squares. Look at your mesh tool, you obviously know how to split different shapes, just move that code to the split tool would make it about 329983% more useful.