Why is the Mirror Universe so Similar?

The Terran Empire of the Mirror Universe in Star Trek is a fascinating and dark reflection of the Federation Starfleet we know. It is complete with alternate reality versions of Captain Archer, the Enterprise, Discovery, Deep Space Nine and possibly even the Dominion but why is Starfleet so interested in it and what narrative reasons are there for its popularity?

00:00 Establishing the Mirror
02:49 The Similarities
04:45 Contamination
06:30 Future of the Mirror
08:22 Fun to be Bad
10:25 Narrative Freedom
12:40 Outro

Star Trek Online developed by Cryptic Studios and Perfect World.
Star Trek Picard/Strange New Worlds/Lower Decks/Enterprise/Voyager/Deep Space Nine/Discovery and The Next Generation are all owned by Paramount Pictures/CBS and distributed by CBS.
This Video is for critical purposes with commentary.