Comic Strips

It's unlikely that insects (or any animals for that matter) are a better use of the land, because ultimately animals need to eat plants, too, and they use up a good chunk of the energy themselves.

Occasionally, you can grow grass where proper crops won't and animals can graze there, but to my knowledge, this isn't particularly relevant in practice, because farmers will typically feed more nutrious food to minimize the time until the animals can be slaughtered.

You talk about complete protein, by which I assume you mean the amino acid distribution, but I find it hard to believe that the inefficient land use of animals is offset by them converting some of the amino acids to be better suitable for us.
Because ultimately, if you manage to grow more lentils and whatnot, you can totally just eat more lentils to reach your 100% of each amino acid.
Wealthy cultures eat significantly more protein than is actually needed, for example.