Well, for one, the shape (and colors) of the blocks can inform the user what can and can't fit into the arguments of a function (can't put the pieces with squar

Well, for one, the shape (and colors) of the blocks can inform the user what can and can't fit into the arguments of a function (can't put the pieces with square pegs into the functions with round holes). Or, in your case, what sorts of values can be assigned; the attributes that use colors look different than the ones that need a date and time. Also, the blocks can make it clear where something necessary is missing in the program. Nothing that a good IDE can't do, but all that and more just for the cost of some color coded puzzle pieces.