Peak Performance: Worf can create sens-oar illusions because he's the chief of security on the Enterprise: he has the codes and knows the system. How the Hell did he do it to the Ferengi ship? Why can't they just do that all the time then?
Yeah, there is a TOS episode (Bread & Circuses maybe?) where Kirk and Spock get this gadget implanted under their skin. Later they dig them out of their arm and Spock uses them to fire a crude laser beam to escape from a prison cell.
And then there is the thingy that Worf gives to Riker in A Matter of Honor. Billy Boy uses it to trick the Klingon captain.
It's these one off items and plot devices that can be annoying. If the gadget was that useful then why didn't it appear again as warranted? You could call it a sloppy plot device.