I agree. You should never retire to do nothing.
You may, however, reach the point where its time to do something else.
Retire when your personal projects don't leave you enough time to work for someone else.
Some careers are grueling and demanding and require a younger persons stamina. Retirement makes sense for those kinds of careers.
It depends on what your definition of “productive” is. I didn’t plan on leaving but the Baraqqi Depression flushed me out.
When you lose a middle management type job, at age 62 you’re not going to get back into the workforce at $100k+ very easily.
So now I receive two checks every month signed by Baraq Obama and enjoy my grandkids, LOL.
For us, it's to enjoy taking care of our grandchildren. I have no regrets about retiring early, after getting laid off. My wife retired early, due to illness from cancer for which she is undergoing treatments. We also took in my wife's elderly mother into our home to care for her, a full-time job. We are not at the end of our productivity, we just shifted gears. Our jobs were not our lives. Our families are.
My neighbor growing up spent his entire working life preparing for retirement. Never went on vacation, deferred everything to save for his retirement. Well the day came to receive the going away watch, and within one week he dropped dead. True story. Since that time as a teenager till today as a 50 year old, I have vowed to never retire.