Personally I thought it was too harsh. Yes the teams screwed up but the league has done themselves a disfavour by relegating Juve, Lazio and Fiorentina to Serie B. Juve's deficit in Serie B means that the team will unlikely gain promotion to the top league at the end of this season. A killer for the sport and a disservice to the innocent players and fans who have been needlessly punished along with the guilty.
A better plan would be to heavily fine all three clubs + AC Milan, have Juve play off from a deficit of 30 points (less for the other two clubs + AC Milan) but keep all parties in the big leagues. Money from the fines could then be distributed to the lower clubs.
This will ensure a better revenue flow for the league (which helps professional development)whilst punishing those clubs who erred with the appropriate gravity.