100% agree; the safety briefing is part but not the only part of that education program. All sorts of information can get embedded into the public consciousness,and there's no reason why "you don't take your luggage when evacuating" couldn't also get into people's minds.
What actually needs to get in to peoples mind is:
"if you take your luggage it will be impounded and at best it will be weeks and a hefty fine to get it back; if you leave it on board it will likely be returned within hours"
Best way to get it in to people's minds is to implement the confiscate/impound carry on rule and then the first couple of times it happens make sure that the complaints from people whose carry on was confiscated on the tarmac are widely aired along side the "you were warned" explanations.
Most evacs (fortunately) end up being precautionary and I suspect many pax are aware of that, even when the result is bad as in the recent event it may not be obvious to those on board -when making the decision- to grab bags.
That is why focusing on the safety issues is not all that effective since the danger is somewhat theoretical.
An interesting statistic would be % of passengers grabbing bags while leaving the miracle on the hudson landing where it was likely obvious to most that it was a true time critical emergency.