I tend to agree with you. While some may criticize the media for reporting on the Holy Father’s address, he is the one who chose such a public format to air his sharp criticisms. This is not the approach that I probably would have taken.
However, as far as I know Francis was an effective leader back in Buenos Aires, and seems to be fairly media savvy. So he presumably had a good reason for his approach in making this address. What could it be?
Sometimes such a public rebuke can be used to hold people’s feet to the fire, so that the public will hold them to account in the following months. However, these are not public officeholders, and the work of individual cardinals and their underlings is hidden from the public.
More likely, he is making his case for a coming bloodbath of reorganization in the curia. He is trying to put the “gossipers” on their back feet, so that their efforts to undermine his reform will be less effective. If he pursued massive institutional change without making this case ahead of time, there would be incessant complaints that he was weakening the Church with such disorienting changes. But if the rotten curia is already weakening the Church… you see the line of thought.
So I think it’s basically a PR offensive which will allow his upcoming curial reforms to proceed more effectively. That’s not to say the scolding is completely undeserved - but scolding a big dysfunctional organization, or the members of a big dysfunctional organization, is not likely to bring about a repentant and suddenly functional body.
