My primary motivation for the payment protocol can be seen in this mock-up of multi-signature transaction authorization:
https://moqups.com/gavinandresen/no8mzUDB/p:af7339204
I want much more secure wallets, but we can't get there unless the "who am I paying" piece is authenticated.
You should save the "Gavin is trying to impress evil institutional investors" mud-slinging for when I get around to laying out the argument for increasing the block size, because that would be closer to the truth.
I tested the payment protocol waters and I'm able to create payment requests with arbitrary output scripts, and I was wondering if there is a way to set transaction inputs as well, similar to what the quoted mock-up hints with "From wallet: Capital Spending Account (current balance: 198.4 BTC)"? Say I want to request that a user signs a full transaction with inputs and outputs, e.g. to redeem dust, would that be possible somehow? As far as I can see it is not, but this comment really made me wonder..