Because the game itself isn't going against my interests. Supporting Origin itself is.
I'd like to support EA where they make the right moves(ie. back around the time they were pushing new titles like Mirrors Edge and Dead Space). In light of their recent bullshit, though Titanfall doesn't appear to be harmful itself(no preoder in-game nonsense, no micro-transactions), I simply refuse to trust EA of all companies with my digital library.
I'd like to push them in the right direction. Too bad they don't give me the option.
Why is supporting Origin against your interests? The service is stable, downloads are fast and the interface is clean and easy to navigate. If you wish to reward good behaviour then surely you should be supporting Origin?