Need is perhaps a strong word in this situation. Whether you need to calibrate your monitor for photo editing truly depends on what your end goal of the photos is. If you are a casual photographer taking pictures for fun, calibrating your monitor really isn’t necessary. But, if you want to up your game and have full control over your work, then yes, you should calibrate your monitor. And if you are editing photos for prints, you definitely need to calibrate your monitor for accurate and repeatable print results.