If you believe in a card long term, whether because of the artwork, the Pokmon, or a gut feeling about where collector interest is heading, grading it locks in the condition at whatever state its in now
It's notorious for a few reasons, and unsurprisingly, it's the usual story of scalpers ruining it for Pokmon trainers and collectors, causing chaos to the point that the museum stopped giving out the card
You'll want to save Jetmir for when you're able to swing out at an opponent, casting him after your opponent attacks or when an opponent taps out
Doubling up triggers for cards like Terror of the Peaks or Craterhoof Behemoth could easily help you close out a game
Master of Death Someone realized they couldnt make a zombified Squee, Goblin Nabob, since Squees immortal and all, so they made Master of Death instead
However, that's the nature of how strong the demand is for these products on the secondary market