Is it only a matter of time, though? "More evolved" means "more adapted". I think that organisms with fast reproduction cycles generally adapt faster. But it is probably difficult to define a scale for adaptation as well.
Yeah they're an expression of an "evolutionary clock" that ticks faster for species with shorter generations. But then there's also evolutionary pressure from surroundings, niches left empty after disasters, etc, so trying to measure any of that is just not very objective. And you have to remember there is no "goal", no one direction, it's a brownian walk so mutations happening faster doesn't really change anything unless there's enough advantage in them.
