For me, I'm running on shoestring budgets these days, and short on truck space too. And since I do most of my loading/prep for a show alone, well, these cases I can't lift myself means I am sorta stuck.
I won't argue the facts though. The case almost ALWAYS costs less than the gear it's protecting. And cases should be considered ALWAYS. Bags are OK, but they have their limitations as well.
For me, cases are an option, an option I rarely have the option to excercise. I wish that wasn't the case.(pardon the expression!) Since I'm struggling to survive in an area flooded by bottom feeders offering trash services for equally trash prices, I can't compete when people shop by price, not by "well, what do I get for the money". So many show promoters hire a DJ to do their sound for an event, only to realize at the last second that "uh, we're boned". Or, there's a bunch of idiots around here using my name without my permission(don't even know them) and so they are going around doing trash work and damaging my name and reputation. Since promoters don't want to give me their contact information so I can track them down and force them to stop that behavior, I'm just extra boned.
Personally, I wish I had a bigger truck, a lift gate and people not abusing my name and reputation to screw me on jobs. That way I could get a bigger truck and get cases!