[GordonS]

I guess another factor is space.

For one thing you can go more 3D with crickets, whereas with chickens you would have to build additional levels if you wanted to 'stack' them.

Also, many people care about the welfare of the animals they eat, such as making sure they have space to roam and live some kind of life before they are slaughtered. I doubt anyone will care if you cram crickets in so tight they can barely move. So at least in terms of space, I imagine you're going to need much less land for a cricket farm.