Are you suggesting that we should never regret anything, then?
Like I said, everything must be in moderation. Regrets are effective for reminding us not to repeat the same mistakes. But of course if we regret our mistakes 24/7, it will only depress us and discourage us to do anything.
Yes we should not regret anything. Regret is not effective for reminding us not to repeat mistakes ( the experience of the mistake is enough to do that, and not the same as regret)