Because the publishers/producers took the risk. They paid you for your work, didn't they? Move on instead of complaining. Yes, it's hard finding work in the entertainment biz (much like sports and arts), but having to pay more residuals than bargained-for only takes away opportunities for you and others to get more work.

Again, I am not against residuals, but a contract is a contract and the right to contract is between individuals. Any "force" (unions, government) that twists and turns the right to contract is anti-individual, anti-freedom, and most certainly a group vs group powerplay that does not give the average individual any advantages - only the empowered individuals gain anything (at the expense of the unempowered).