I've long struggled with what monsters to throw at low level characters, to the point of crafting elaborate tribal societies for kobolds, with shaman, witchdoctors, and thralls from tougher humanoid tribes to fight for them. I think I was missing the point, old school seems to be about letting players decide if they can handle a battle or not, this will always be the case (run from the Balrog!), so throwing weaker monsters at players seems to be the wrong solution.
That being said, low power monsters are not necessarily a bad idea, thus this series: Deadly Distractions. These will be very low power creatures that could cause problems even for higher level adventuring parties, depending on how they handle them. And that's why I like them, they add another player choice (is this thing endangering us?) to the more common one (should we fight or run?) that they face when encountering a creature. And player choice is good.