It's more just that your day to day *should* change over the course of 15-20 years. What I'm referring to are situations like people who have current day to days that read exactly the same as it did in the early aughts. For instance poking at pre-generics Java to parse XML files, populating some enterprise beans, and pushing to a web page using whatever the heck framework was in vogue back then.
There's nothing wrong with someone turning their brain off and working in that role for 20 years. But they shouldn't be surprised if their experience is completely irrelevant in the modern job market. If one wants to develop new experiences and their job won't provide that over a long period of time (say 5-10 years of employment, not every 6 months!) then it's time to consider the tradeoffs you're making.
There's nothing wrong with someone turning their brain off and working in that role for 20 years. But they shouldn't be surprised if their experience is completely irrelevant in the modern job market. If one wants to develop new experiences and their job won't provide that over a long period of time (say 5-10 years of employment, not every 6 months!) then it's time to consider the tradeoffs you're making.