As frequent SLF, I am well aware of the instructions to leave everything behind when leaving an aircraft in an emergency. What is not clear to me is the relative importance of not being encumbered by a bag when going out through the door and down the slide compared with the delays and congestion caused by people extracting luggage from overhead and under seats.
My expectation is that once you are at the door, the fact that you are hugging a suitcase as you jump is of relatively minor importance.
The most obvious way to avoid cabin congestion and delay, whether during regular exit of emergency evacuation, is to limit the size and quantity of hand baggage.
Airlines should set reasonable size rules, and enforce them. And to complement this, they should not charge for reasonable quantities (size, weight, number) of checked bags, and should also ensure that bags get to the carousel as soon as the passenger. They could start by separating terminating and transferring bags at the departure airport, cutting one process and its delays from the delivery process.