As a rule I don’t play any of my basses unplugged. I have, and my best sounding basses were not the ones that sounded best unplugged. The amplifier is part of the instrument. Playing it unplugged is like removing the bell or the reed from a saxophone. I don’t care how good half of the instrument sounds.
Also, playing unplugged encourages playing with a heavy touch, and you won’t hear any subtlety of your technique.
I was about to say the same thing, especially how playing unplugged reinforces a heavy touch. Do it enough (just like grooving a tennis stroke or a golf stroke) and you train yourself to consistently have a heavy touch. Not my cup of tea.