cars were made of shittier parts no doubt but the fact remains the added complexity of vehicle design nowadays does mean an increased rate of subsystems failing for seemingly no good reason.
having said that, i don't see how added crumple zones mean the vehicles are manufactured to any better a standard. the actual assembly process hasn't changed much for the mass-produced cars that compete for the under-30G market, but now a lot more of the parts going into them are being shipped all over the planet to divvy up the labour.
the names that produce high-end cars, like lexus, differ greatly in the creation process by keeping a great deal of the work in one factory and using labourers that are trained to do more than just put a piece of metal into a machine, press a button to stamp it, then put it into a pile with the rest and repeat for 40 hours a week. they actually employ people with a fucking brain in their heads and pay them well for it.
this obsession with specialization that the usual suspects are prone to saves a lot of cost but it also means there's less pay going to the labourers in the factory putting the cars together so naturally the expectations from those labourers in terms of quality are getting less and less.
sure, the engineers are paid more because the technology is a lot better now than it was 50 years ago but the average factory workers who are the guys actually putting the damn car together and making sure nothing is fucked up between the design table and delivery to the market are getting stupider and lazier.