I personally like the dent. It's not a feature that would sell the knife to me, but it makes the lock easier to disengage in certain situations; such as when the locking bar is wet/slippery, I am wearing gloves, or I'm not looking at the knife ( less frequent, but not unheard of). And as for asthetics, repeat after Sal: A tractor does not need to look like a Ferrari. Which does bring up the interesting point about the kopa and the kiwi having dents and the manix and chinook, arguably the most tractor-like in the line up, not having them. Mabey I'll just have to buy all of them and let my hands decide.
The dent is designed to be centered when the lock hammer is at its highest point. Considedring the arc of rotation, it will never be centered when the lock hammer is in a fully opened or fully closed position.
The Chinook and Manix models have a much smaller lock bar opening in the handle and the hammer must be lifted considerably higher to desengage the lock.
Mike Janich gave us quite an education on accidental lock release with lock-backs. Cliff Stamp was also quite helpful in this development.
Spyderco designs are always a "work in progress" contantly being refined and improved as we learn more about function, safety, materials and ELU preferences.