Locking overhead bins
Hopefully the recommendations made by the AAIB in their report will lead to EASA introducing regulations mandating the locking overhead bin solution. It seems to me to be the only practical way of stopping passengers evacuating with their luggage.
As for dimming the cabin lights, it serves multiple purposes. Yes, it aids in developing a form of night or low light vision, but it also reminds passengers that they can expect the exterior of the aircraft environment to be dark. Air travel enables people to cross multiple time zones and international travellers may not always be aware of the night/day situation. Finally, the CC need visibility out of the aircraft prior to deploying doors and slides. A darkened cabin during the hours of darkness enables them to see out of the windows.