It doesn't have anything to do with in-flight safety, but they may cause delays and disruptions. The FAA may go in and inspect and the airlines might not be able to prove that it's in compliance.
All in all, it's a formula for lots of delays and long lines.
Fares will be down, crowds will be up, delays will be longer. You're more likely to be in the middle seat, or next to someone in the middle seat, or sitting at the gate because you got bumped off the airplane.
Canceled flights really irritate passengers tremendously, because you're stuck, and you usually can't get out of an airport for a day or more, and so it really disrupts their travel many times more than a delayed flight.