Evolution is lazy and a spendthrift. Sure, it drives change, but it will cling to anything that is just barely good enough. As a result, every creature alive today has bits and pieces that don’t work so well. For example, humans are prone to choking and sinus infections because our resperatory pathways are fairly terrible for a mammal walking upright. Any worse and they’d kill us more often than not. But they’re just barely good enough.

The benefit of design is that, in theory, hundreds of years down the road (I am not an optimist when it comes to complex genetic re-engineering becoming viable in the near future) we will be able to look at the laundry list of broken and out-dated pieces on the human body and give them a bit more rational design. Randomness is what drives evolution when there is no pressures but those of nature. Design is able to take the errors from that randomness and refine the resulting entity.