I was considering not to reply here, but I will out of respect for Numsgil.
Lets try something theoretical here (because I know how much you love theoretical stuff)
Lets say instead of the way venom works now you need 10 different chemicals (that is, you need to store to 10 separate memory locations) to achieve the same result. Why would a robot magically evolve 10 unique stores all at the same time? It is already having trouble evolving 3...
So I do actually agree here that it will not take me 5 years to evolve something.