It’s a good question to ask yourself BEFORE you ride a bunch of intervals. If you ask that question during your interval session, you will loose focus and reduce your performance in the actual training session.
Thus, if you have decided to do a specific interval training session, then make a short list like: Arguments why I need intervals. If you suffer during the intervals, you can repeat the arguments, but don’t start a new discussion of whether you need intervals or not. That discussion has already been taken. Bump.