These restrictions are meant not only to ensure passenger safety, but also to create an equal amount of carry-on space for all passengers. Anyone who has taken a flight recently knows the system doesn't work. Most passengers prefer to put their bags overhead so they can have more legroom. People who get on the plane first tend to stow both bags up there. Soon the bins fill up and people who board the plane later cannot find overhead space.
Passengers become frustrated as they scurry up and down the aisle looking for an open bin.
Flight attendants get flustered and often have to gate-check extra bags. As a result, the departure is usually late by a few minutes, and if it isn't, it's because the airline has factored this wasted time into their schedules. In short, no one is happy. People Differ Airlines need to recognize that people are not all the same. When you spend time at the baggage carousel, you're giving up some other use of that time.