Do you want to ruin Bitcoin?
Because allowing fractional reserves would be a good way to ruin Bitcoin.
Too think off requiring 100% reserves as being anything other than one of the only positive requirements of these rules is nothing short of idiotic.
People should have a choice though. I would save 90% of my BTC in a "vault bank" and would take the other 10% and put it into a fractional reserve bank account hoping the interest payments made up for the risk.