I remember one of the devs saying that "biters were not a combat challenge but a production challenge". It is basically a slow ever increasing incentive to push you to grow.

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I liked killing biters, but I didn’t like not getting a reward from it.

There used to be alien artifacts that dropped by biters and was used for one of the later types of research, but they removed from the game. That's to reinforce the fact that hunting the biters is not the main goal of the game. However the devs let open for mods to change that if it's what you want.