Forced to sign luggage waiver before flight

I was forced to sign a waiver when travelling with skis in January. After making the booking, reading all the Ts & Cs, arranging connections, accomodation, etc. etc., I get to Tullamarine and I'm told "If you don't sign this waiver, you cannot fly today." The waiver basically says "Jetstar can completely destroy your luggage and you agree to do nothing about it."

This is illegal. Consumers should not be coerced into signing a legal document at the last minute, after having already purchased and agreed to all conditions. I had my ticket, the deal was done. But then I get threatened with not being permitted to board at the last minute unless I sign, while I am standing there with my family, trying to check-in.

What else could I do - I had to sign. Completely unforgiveable Jetstar.

International
Australia-Melbourne - Tullamarine
Japan-Tokyo (Narita International)