Also, we're incapable of cloning things that don't have serious health problems and, usually, dramatically shortened life spans. ^^ So the Yeerks wouldn't be much better off takin' our technology. Moreover, no matter how much effort it is to breed a Hork-Bajir baby, you're pretty much definitively better off than you would be cloning it- it took 277 attempts at transfering the specific sheep's DNA into ovum to create Dolly the sheep. 29 of them managed to make embryos. Three of those embryos survived to birth. Only one of them survived to adulthood. She lived about half of a sheep's lifespan.
Our latest attempt at cloning, according to Wiki, was a water buffalo that died when it was five days old.
One would think the Yeerks would have better technology than our's, but perhaps they just steered away from biology. ^^()