Is the criticism of representative agent models.
Represenative agents aren't the end of the world, of course, but I think they're very misrepresented. All representative agents give you is a macroeconomics grounded in optimizing behavior. That is the sense in which they are "microfounded". A better word might even be "optimization-founded". That's an important technique to use, but it's not entirely satisfactory. Agent based modeling (or something else other than representative agent) is what really gets you microfounded models.
Do agent based models get you substantially different insights than well done representative agent models? That I don't know.