Henchman NPCs and NPC groups can be very useful for getting the PCs out of various pickles they find themselves in.
And they will find themselves in pickles. PCs virtually live in pickle jars.
GM: You round the corner, with the trooper in hot pursuit.
Han: Excellent, my plan's going perfectly.
Chewbacca: What plan?!
GM: You run into the rebel battalion, weapons out. The trooper stops and surrenders.
Major Derlin, 2nd Lord Clabburn of Hoth: Hold the line, men! This guy's not getting through.
C-3PO: I did not see that coming.
Leia: Why didn't you hit him on the head like 3PO said?
Han: He had a helmet on. So I improvised and got him to chase me, so he'd get hot, and take his helmet off. Then I could turn around and hit him.
Han: But then these guys ambushed me!
Nik Sant: You're welcome.