For example, I can't vote "against" this proposal except by voting for the "refund proposal"

Exactly. This system clearly is not designed or effective for voting on whether or not a change should be added to an upcoming HF, or anything else where we are striving for consensus. This is simply tracking whether or not there is enough support for something to get the funding it needs.

Whoever thought of a voting system where you really only get to vote "yes"...

The below mentioned two proposals at least allows for disagreement, but without linking the two proposals, most people would probably only see one of them anyway.