I know of a forklift that's pushing 80 and still used in a lumber yard (i.e. a material handling centric workplace)
Other than ~30min it takes to teach an employee to drive manual it doesn't do anything worse than the modern ones it works alongside and it does a handful of minor things much better by virtue of predating OSHA.
Wasn't designed with the assumption that when someone gets hurt lawsuits and fines could/would fly and so there's a lot less of the manufacturer covering it's ass in the design.
There's nothing to keep you from putting it on two wheels and the transition from on the ground to off the ground is pretty graceful and operator friendly whereas the newer lifts rely on a pressure release valve to keep them from lifting that much and (presumably) because they were always expected to be far from ragged edge their weight distribution is not really proper for that. The counterweight is substantially taller so how hard it pushes down is reduces more quickly as the lift comes up so it lifts tire further (and is more likely to dump the load or go over). This also means the old lift has a way lower ass pucker factor when doing stuff at max height. The real nuisance is when braking though. Yeah you "shouldn't" brake with the load up but operators who get good will raise the load at speed as they are coming in to put a pallet of stuff on top of another pallet of stuff and then when they brake it can get sketchy. The new lifts do corner much better unloaded though so I guess you could be much faster zipping through a warehouse on a new lift (but what workplace would permit that? And top speeds are about the same so there's no benefit in a big outdoor workplace like say an airport or shipyard).
There's no seat switch or other safety interlocks so you aren't putting a ton of wear on it if you're constantly getting out to fiddle with stuff. This also means you can do "unsafe" things like stand beside it and wrangle something and just reach in and make the mast go up and down. While in a textbook world this is "bad" and you "should only pick pallets" and "everything should be strapped to the pallet" in the real world you make all that back and more because it means you can use the forklift as a glorified engine hoist/shop crane without a helper. Hook and chain operations are made much safer/more reliable by this too since the operator can be sure things are good and is not tempted to half ass it to save the time of getting back out. Sure you could always add a helper but that's dangerous too because one person doing stuff near equipment and one person running equipment opens the door to miscommunication related injury that can't really happen among one person.
I'm sure "at scale" the new lift is safer, but safer for who? In what operating context? How big is the difference?
Other than ~30min it takes to teach an employee to drive manual it doesn't do anything worse than the modern ones it works alongside and it does a handful of minor things much better by virtue of predating OSHA.