I am 100 percent in favor or lockers in Hostels and even in Hotels, the locker being big enough to put my two carryon travel bags inside. I want a hasp that allows me to use my own padlock, and consider it unsafe when the Hostel has a way to enter my locker. I do not trust cleaning people, some minimum paid person who has access to all my possessions.
I am not in favor of padlock solutions - because not every traveller has a padlock. Our lockers work with electronic smartcards. Our cleaning staff can only open the room doors, but not the lockers.
I truly wish they would put electrical plugs inside the locker for mobile phones, computers and other electronics to keep them safe also.
Fire hazard! What if a charger overheats and catches fire inside a locker?
However, I am 100 percent sure a locker inside the dorm is the worst location for them. They should be located outside in the hall whereby a person can wake up for their five oclock flight and not disturb all those who stayed up all night drinking.
I think most people would consider that to be unsafe. When the locker is in your room, you will wake up if someone tries to break into it. You won´t notice if that happens outside your room.
I will say thank you to the Hostel that do have lockers, as best I can estimate, only about fifty percent even have locker and care about the guest safety. I lock my bag up to the bed with dog chain.
I always did that, too. Best of all, you can lock up your bag inside the luggage compartments of buses. When I travelled in South America, a backpack vanished from a bus - not mine. If luggage is transported on a roof-mounted rack (very common in countries with bad roads and old buses) you can lock it to the rack so it won´t fall off.