The best thing about a steady job is that it takes worries out of your mind, you're not always stressing about losing your job and making ends meet. That's the most important thing that many tend to underplay.
This is the scenario that worries me- a massive race to the bottom in order to get "ahead". Most jobs aren't that important, and don't merit that much of the employee's time. At an e-commerce place I used to work, I overheard a c-level exec tell a guy who was putting in lots of overtime, "Remember, we're not curing cancer here." I think it's great that the exec was encouraging the guy to not place too much importance on his job, but it's too bad that it was necessary in the first place.
It's clearly the right approach (particularly in tech) but corporate culture is what dictates if this is accepted where you're actually working. If you work at $OLD_SLOW_COMPANY then it's less likely to be understood then at $SMART_YOUNG_CORP.
> And I don't think many of us expect to work for only one or two companies our entire lives.
Spot on. The usual advice I give is to plan on staying at a gig (as an employee, not a founder) for 2 years. Year one is for learning, year two is for shining. By the start of year three you should be either off to apply what you learned elsewhere or doing something new internally. The two year number is somewhat tied to the bonus/promotion cycle of the financial services industry but I think the general idea applies to all fields.