This is a terrific idea. Many on the losing side of a match-up work hard too, and lose plenty in resources. An Estoc Edge bonus to rebuild sure would be helpful to recoup these losses. Win or lose, we all get back on our feet faster to War again.
Please don't shoot down this idea for selfish reasons, that your current privileged earnings will diminish. There is no War without competitors, and bringing new Kingdoms into the fold is paramount.
Winners still get much better prizes after all.