Jeskai Energy plays a dense package of efficient interaction (Consign to Memory, Spell Snare, Wrath of the Skies) alongside proactive threats like Phelia, Exuberant Shepherd and Ragavan, Nimble Pilferer, so Thoughtseize lets us proactively strip a key piece of interaction or a threat before they can leverage it against our graveyard plan. Lightning Axe is clean, cheap removal for Ragavan or Phelia that dodges their counterspell-heavy suite since it's an instant they have to actually see coming. Burning Inquiry is too risky against a deck with cheap efficient answers that punishes us discarding our best cards randomly, so it's cut, along with Golgari Thug whose small body doesn't hold up well and doesn't advance our race fast enough.