As pointed out, it is an indication of the care taken in manufacturing, but a blade that isn't centered can rub on the near side and cause uneven pivot wear over time. If it can be adjusted with just a fraction of a turn on the pivot screw you'll get easier opening and avoid scuffing. Most folks didn't worry about it when we were only using back locks, but as new locks and pivot systems became normal it became more important and as custom knives required that care be taken for the money being paid it flowed down to custom designs being licensed and manufactured since the expectation was for properly centered blades.