Cubdriver is right. I have a background in human factors engineering. Many of the systems in planes like and older Seneca and Navajo are simply terrible. There's literally no chance in hell something like that could get certified today. Although humans are amazing at some things, they are poor machines and poor at doing things repetitively or correctly time and time again. If something is required for a safe outcome, this means that a small percentage of the time, it won't happen correctly and there will be an unsafe outcome. I'm very familiar with the PA-31. If the system was designed better, could the outcome have been avoided? Good chance yes. Was it still pilot error in that if the pilot performed perfectly it could have been avoided? Most likely. Is it reasonable to expect a human operating that system to operate it correctly every time? Probably not. I know 737 captains who keep their finger on the crossfeed pump the entire time they are crossfeeding, because they don't want to forget about it and because it has happened in the past. Why has it happened in the past? Systems like that are designed without adequate protections for human factors.

Good comparison is the GA-8 airvan design. It's a single engine, but looking at the problem of fuel balance, it's an absolutely ingenious solution, instead of having the right tank feed the right side of the reservoir, it feeds the opposite side, and it's designed to take fuel from whichever wing is lower/heavier, thereby it continually keeps feeding from the "heavy" wing, with no ability to select left or right, just a steady flow of fuel. It's designs like that which should be incorporated in aircraft design, still requiring you to track fuel burn, just not perform some unrealistic 4-tank or more management and try to guess when each tank is reaching it's end or other monkey magic.

None of these systems are likely too hard to overcome if you have all the time in the world and blue skies, but you start stacking tasks on top of each other and you start to get close to a point where something will break, which is more likely in many of these late model piston aircraft. There seems to be a point at which they went kind of crazy from relatively simple and few systems to far more complex and numerous systems, to add more features and capability. Now certification rules and standards are higher and many of these issues are designed out of the system in new aircraft.