The 'set and forget' aspect of this is appealing. I've sometimes wondered if you could automate the whole thing, including option generation. If you can define good enough mutation functions you could have your features literally evolve over time, without developer input. You'd need a lot of throughput to get reasonable evolution rates though. Jacking up the mutation rate won't help because really big mutations will break the layout.
It's almost certainly impracticable, but fun to think about.
But truly someone has to design the learning system, at some level you will always have design, if it is the design of how the design is to adapt to it's environment.
It's almost certainly impracticable, but fun to think about.