Well, thats mainly down to the rider of needing seven or more Plains in play for it to trigger (and maybe a little because some white decks cant tutor it, so folks tend to undervalue having access to it)
It is still a very powerful card, but the effect is basically just a Fireball and even though X-spells are now rares, it doesnt feel like a mythic despite the upgrade
A few categories are worth prioritizing regardless of which deck you choose: Ramp Commander games run on mana
If you can keep a key piece in play, it means youre able to spend mana on other pieces that synergize with it and eventually, this means youll get closer to a win a lot quicker
Its one thing for a combo to win a game and end it, but the worst banned cards will stop your opponents from doing anything from early in the game (think about cheating out a Sundering Titan on turn 1), but wont let you win for a long time
If you can, an idea opening hand would be Maleficent Biding Her Time or Lilo and Madam Mim Snake, alongside either a Pinocchio or an Arthur