I think I finally figured it out why they make us stand so much! Just be advised that it is not a very Christian answer but I wonder if there is some truth to it.
Ready?
I think they make us stand so we can reach deep into our pockets before the collection plates come to collect the tithing.

You know, if you are sitting you can only reach a little bit. If you stand you can reach way down in there.

Anyone? Possibly?