My main idea for choosing to stay mostly red is that it means
Blood Moon doesn't really hurt you that much. Actually, against many of the Eldrazi decks, without their nonbasic lands they have no way to produce colorless mana, other than maybe a singleton or doubleton
Wastes. So, especially with fast mana in
Springleaf Drum and
Mox Opal, you can land a turn 2
Blood Moon and lock them out of
Reality Smasher,
Thought-Knot Seer, etc., while you still have all the fixing you need from the aforementioned mana rocks.