I've never calibrated. I just purchased the BenQ SQ2700pt monitor. Windows 10 installed the BenQ profile, I have it running in sRGB. My photos looked flat. On the iPad and Galaxy S6 they looked great. They looked good on prints. I did a lot of testing and found that it was the monitor profile, I switched it to sRGB and it looks normal again.
Any need to? I've always been happy with the prints. I do need to order some prints of photos that I've edited on the new monitor to make sure they line up.
I'm not sure if I want to spend a couple hundred dollars on a calibration kit if it won't help me.