Maybe a partial solution would be to seriously limit the size of carry-on luggage, and enforce it. If the bag is small enough, it won't matter if people take it with them during an evac. We're talking big enough for a tablet, passport, wallet, specs, bottle of pills, and not much else.
A two-tier system might be necessary; one small bag to accompany the passenger, another bag accessible in flight (nappies, and other mainly-essential but bulky sundries), said bag to be locked in a cabin hold, available from a flight attendant on request. (Request to be met with a smile, and a polite but firm shake of the head in the event of an emergency evac.)
While they're at it, how about banning outbound duty free liquor. Stuff is a major fire hazard, plus it's heavy, plus it could be used as a weapon.