No need for the agression. There must be a third party in your idea or how else will the network determine the double spend? To the network it will eventually just look like 1 transaction with no guarantee enough nodes saw 2 transactions. So there is no way to automatically flawlessly detect a double spend, a third party is essential to settle disputes. Also your idea with no third party requires code to send coins from addresses without needing the private key which has far too many security implications.
Also if the standard is that people without double the money they are spending in store having to wait 10 minutes, 95% of people will be waiting 10 minutes. Not sure where you are from but most people I know live paycheck to paycheck and a grocery shop after rent and fuel does not leave much.
Also I do not work, have not invested and have never even used bitpay. I have heard how it works and see bitpay as a possible future for point of sale, especially if the merchant does not want to hold Bitcoins at all.
Currently 95% of people will be waiting 10 minutes, but it will open a door for the average Joe from the street to accept BTC as well, ultimately rewarding anyone who holds BTC currently.
Also what makes you think that if we make Bitcoin clients relay double spends that it won't propagate as fast through the network (assuming the double spend is valid), there is no reason to suggest it wouldn't be as fast as the transactions themselves.