Bought my first p/u in 1976. Ended up putting a poj slide in liner in that. Don't recommend that route...seems to be the worst of all worlds.
I've since had both factory and aftermarket spray-in liners..and wouldn't have a p/u without one. I carry tools (in boxes or not), several totes of "goes with the truck gear" (tools, straps, tire chains in the winter, etc), a jack, infrequent lumber or similar goods, very infrequent loose materials (gravel, topsoil, etc), fairly frequent yard debris to haul to the dump, skis, snowshoes, hockey gear, sno-go materials, etc.
I think the spray-in bedliner really helps preserve the bed. On my previous rig, after a solid 12 years of the above-use, I found 1-2 spots where I'd either worn through or gouged through the liner.