Do I really need my parking brake?
 

Looks like some street debri and/or age took out my right rear parking brake assembly.
Took the rotor off and most of the springs etc just fell out into my had.

The other side seems fine. Will the world come to an end if I just continue with one parking brake?

The world won't end with you using only one parking brake. Like its' name, it's a parking brake and not an emergency brake so pretty much the only reason it's there is to save your parking pawl - which is pretty important.

When I first got my car my cables were all seized and when engaged, it did not do anything. That was one of the reasons why it did not pass inspection/safety... I ended up replacing pretty much everything involved with the parking brake with oem parts from Sewell's. Didn't cost much and now I can use the parking brake when I park on an incline or downhill.

I had something similar happen to me. I heard some grinding in the back after I first bough mine and took of the rotor to investigate and had metal confetti instead of a parking brake. The parking brake doesn't work very well with just one side remaining, but you don't really need it anyway.

I'd rather get it fixed, one day it might become useful. And i personally find nothing more annoying than when i know something isn't right.