Every now and then there are questions here about the need for power conditioners and/or surge protectors.
Here is a story about the need for these things.
Here in Carson City we have a small restaurant that closes off the street every other Friday night through the summer and has an outdoor concert/dance. June 1 was the first night this year. A storm moved through town during the day, but began clearing in the evening - everything looked good to go. The band set up and started playing. But the storm was still going a few miles away. Anyway, somewhere else on the grid, lightning hit, and a surge went though the whole city. The surge went through whatever protection the band had and one guitar amp, the bass amp, and one of the PA amps all went up in sparks and smoke. Concert over.
This is an extreme example... and they did have moderate protection - which is probably more than most of us. But even small bumps in the power can damage your electronics. It just makes sense to protect your gear as well as you can. If you spent a few thousand for amps and effects, why not spend a hundred for protection?