Payment protocol does not increase the lib dependencies in bitcoin-qt/bitcoind. Have you looked at the implementation? it's pretty small.
It ties the implementation to openssl lib even more, making it harder (if not impossible) to remove openssl dependency in the future.
And openssl is a much bigger mess the bitcoin at the current stage.
Actually there is an easy solution for it.
There is a minimal version of openssl targetted specifically for low-power embedded devices:
cyasslYou are obviously a low-level programmer, so stop wasting time on the forums and perhaps make Bitcoin compatibile with it.