[_delirium]

Yes, on the latter point: vacation time and pensions typically increased based on length of service with the company. You ended up with a much worse pension if you had 10 years' service with each of four companies, than if you had 40 years' service with one company, under the traditional defined-benefit pension schemes.

There are probably a lot of cultural changes influencing it though, perhaps more; changing jobs frequently as a salaried professional just wasn't something many people in my dad's generation actively considered. One of many factors might be the change in how promotions are done; it used to much more often be "within the ranks". You worked your way up to FooBar VP or even FooBar CEO by starting in a regular job and getting promoted up the ladder, which required staying at the company for a long time. Now it's more common to hire external people right into senior posts.