Dear Joseph,
Alright, I may undersand. Let us say, for example, I'm going to WC and my hands get dirty. Then why one have to wash his feet and head when they aren't dirty? Only hands and private parts that should be cleaned. That's the only logic i see.
Just, one more question. Could you give som details about prophet Muhammeds (pbuh) ablution, if it is not hard for you.
Kind regards,
Haji