Having two different types of regular boosters means we have to communicate twice as much information about how each booster is put together and what's in it
It doesnt take long to build a fleet of dinosaurs John Hammond would be proud of, while Akromas Will, Xenagos, God of Revels and Apex Altisaur mean there are some cards going for a fair amount

Sort Rarity Card Type Fairy Energy Common $0.36 Darkness Energy Common $0.18 Fighting Energy Common $0.21 Fire Energy Common $0.24 Grass Energy Common $0.26 Lightning Energy Common $0.27 Metal Energy Common $0.19 Psychic Energy Common $0.20 Water Energy Common $0.24 Celebi V #1Ultra Rare $2.04 Roselia (002) #2Common $0.07 Roselia (003) #3Common $0.06 Roserade #4Rare $0.23 Cottonee #5Common $0.04 Whimsicott #6Rare $0.24 Maractus #7Common $0.21 Durant #8Rare $0.06 Dhelmise V #9Ultra Rare $0.74 Grookey (010) #10Common $0.07 Grookey (011) #11Common $0.10 Thwackey (012) #12Uncommon $0.05 Thwackey (013) #13Uncommon $0.07 Rillaboom (014) #14Holo Rare $0.30 Rillaboom (015) #15Rare $0.32 Blipbug (016) #16Common $0.02 Blipbug (017) #17Common $0.02 Dottler #18Uncommon $0.03 Orbeetle #19Rare $0.13 Gossifleur #20Common $0.12 Eldegoss #21Uncommon $0.08 Vulpix #22Common $0.21 Ninetales #23Rare $0.42 Torkoal V #24Ultra Rare $0.98 Victini V #25Ultra Rare $1.10 Heatmor #26Uncommon $0.03 Salandit #27Common $0.06 Salazzle #28Uncommon $0.30 Turtonator #29Rare $0.15 Scorbunny (030) #30Common $0.17 Scorbunny (031) #31Common $0.04 Raboot (032) #32Uncommon $0.13 Raboot (033) #33Uncommon $0.09 Cinderace (034) #34Holo Rare $0.32 Cinderace (035) #35Holo Rare $0.46 Cinderace (036) #36Rare $0.37 Sizzlipede (037) #37Common $0.09 Sizzlipede (038) #38Common $0.03 Centiskorch #39Rare $0.27 Shellder #40Common $0.03 Cloyster #41Rare $0.23 Krabby (042) #42Common $0.22 Krabby (043) #43Common $0.04 Kingler #44Uncommon $0.20 Goldeen (045) #45Common $0.05 Goldeen (046) #46Common $0.06 Seaking #47Uncommon $0.10 Lapras #48Rare $0.30 Lapras V #49Ultra Rare $2.86 Lapras VMAX #50Ultra Rare $5.71 Qwilfish #51Uncommon $0.11 Snorlax VMAX (Secret) #206Secret Rare $106.91 Snorlax VMAX #142Ultra Rare $61.97 Marnie (Full Art) #200Ultra Rare $38.15 Snorlax V (Full Art) #197Ultra Rare $35.04 Morpeko VMAX (Secret) #204Secret Rare $26.37 Marnie (Secret) #208Secret Rare $23.16 Zacian V (Secret) #211Secret Rare $21.58 Lapras VMAX (Secret) #203Secret Rare $20.89 Zamazenta V (Secret) #212Secret Rare $14.54 Sableye V (Full Art) #194Ultra Rare $13.32

The big downside is that unless youre playing Amethyst there arent any good Shift targets
Eye of Ugin Lands that tap for multiple mana are often busted, but Eye of Ugin takes this further by providing cost reduction that multiple Eldrazi spells can take advantage of
If both are heads, discard cards from the top of your opponent's deck equal to the number of damage counters on this Pokmon