Cant see the link from my mobile, so I am confining my post to the concept of tithing in general. The concept of sacrifice to God has been around a long, long time. I do not think it is valid then to say that the concept of tithing (either in animal sacrifice or money) is or was drummed up to merely fatten the pockets of those in charge--this concept is also found in unorganized religion as well.
I think that there are lots of places that do try to guilt you into giving money, but that is not all places.
the concept of a sacrifice (whether money or not) to God is an act of a) thanksgiving for what you have and b) an act of faith that God will continue providing for you. in addition in the early church tithing was voluntary, and as a way to help the poor among them. And further, one could legitimately say that although God has no NEED for your money (i do not think he does), He probably does want you to be concerned abput people other than your own interests/families interests...and giving money is a way to help out others.
It's kinda (ok, not really, but I cant think of another metaphor at the moment) like a father who gives kids chores, even though he has servants to do chores for him. Does he need the kids to do them? Nope. They could get done anyways. Is it a way to teach responsibility and perspective? Yep. Maybe even make the kids thankful they don't always have to do the chores (ie--thankful for the money, home, whatever you do have).
Anyway, that's my take on it. I am sure there are lots of places out there that do misuse, misallocate, and abuse tithe money. And I am sure that there are places out there that use every penny to help the poor/whoever as best they can. Should that reality affect the concept of tithing as legitimate? No, only your choice as to who you give your money and time to.