For magicians, a gimmick is a device that is employed to make their sleight of hand more remarkable.
It does most of the heavy lifting and augments what the performer is trying to pull off.
On its own, it’s painfully obvious to an audience there’s something being used and ends up denigrating the magician.
However, as an enhancement… the magician looks like a miracle worker.
Our world is filled with gimmicky methods in the quest for our attention. It’s only a matter of time before we figure out there’s no substance behind many of them.