Yah but if you get crap 95% of the time, then you're "wasting" an improvement 95% of the time. I mean, maybe the Level 1->2 guardian unit isn't so badass, but I would expect something rather awesome for 2->3 and espiecially 3->4.
Remember you're frontloading your benefits. Instead of having an increased production for something for the rest of the game, you're frontloading that into a strong earlier military presence. It shouldn't be SO strong if you get one and no one else does, you insta-win. But it should be strong enough that if someone is focusing on econ and only has a marginal army, if you bring your marginal army + your guardian unit to fight you should win without too much struggle. (the Rock-Paper-Scissors of strategy games: rush beats econ which beats turtle which beats rush. the guardian unit appeals to both turtle and rush strats. The thing is that econ is ALWAYS the strongest choice right now).
