You can't flip them in Shiko decks, if you are making token copies of them, but I think getting their ETB abilities when they come into play is enough value
Magic's best sword is essentially a mana-doubler with disruption attached, and the twin protection abilities make it easy to connect against someone
The set also introduced new gameplay mechanics, such as Pokmon Tools and Baby Pokmon, adding layers of complexity to the trading card game
And with the release of Time Spiral (2006), Threshold was retroactively changed into an ability word, and all previous cards were given an errata so that "Threshold -- [effect]" now read essentially as a reminder of the condition while also aligning it with other ability words like Metalcraft ( which cares about having three or more artifacts ) or Morbid ( which checks if a creature died this turn )
Factors like print quality, exclusivity of releases, market recognition , and collector demand all play a role
Its even got partner to pair with other colors