This is a list of Wild Mass Guesses which are silly and just for fun. If it is Confirmed, please move it to the confirmed page. If a WMG is Jossed, please move it to the jossed page, if it is open, please move to Open Theories Page, if it is partially jossed or partially confrmed, please move it to Partially Jossed/Confirmed.
Dehaka collecting Terran essence didn't just upgrade their combat ability.
They also absorbed new skills from the Terrans' genetic history like diplomacy skills (could be handy if they decide to do mercenary jobs for Terran contractors, and request payment in genetic materials), advanced tool making, speech skills, psionic potential, and so on. This may lead to more ways to gain essence besides combat, such as trading with Protoss and Terrans. They might have even developed a taste for Terran beverages so that they can sit down discuss business.