Definitely agree on this idea. Seeing a potential for a long list of year long project to cull through. Would there be a way or consideration having secured funding for an initial phase that it might assist, in someway, with subsequent phases. The reason I say this it that you might get funding for the first phase, might be flashy and cool, but phase 2 might be a little more mundane and not so flashy - may potentially derail a project if a second phase can't get the funding required to continue on.
I can see it forcing the proposal creators in to having to think more strategic about their road-map... but a potential concern; on the other hand as I type this it may not be a concern at all... just be more strategic in your road map. Feel it's still a solid idea to increase the cost.