The proposal I reacted to made no mention of it being a setting, i.e. optional, however.
Ah ok, so just to make sure everyone's on the same page, this is the screenshot from the Missive:
The idea was to make it "ticked" by default, and it's a per-wallet setting, but if people want to disable it or increase/decrease the percentage they can at any time. Before the GUI is even released, though, we wanted to add this in to simplewallet / rpcwallet - again, prompted during wallet creation, and configurable at any time.
Now I know this seems like a small amount, and it won't do much difference, and you're right. This is not going to satisfy the immediate and large funding requirements. Which is why this is more of a longer-term thing to make sure we always have budget for ongoing efforts / maintenance. It does not preclude fundraising for specific features / tasks.