Esper Control is full of blue spells (Teferi, Narset, Day's Undoing, Consign to Memory, their own Mystical Dispute) so your Mystical Disputes come in cheap and are excellent at stopping a counterspell or wrath. Into the Flood Maw bounces a problematic Solitude or blocker cheaply to clear the way for your combo. Nature's Claim has no real targets against this deck, and Veil of Summer is less necessary now that Mystical Dispute covers the blue side of their interaction, so both get trimmed for the more impactful swaps.