Having revisited MtGO to get an updated perspective, I found that metagaming against Thoughtseize made me the most happy. Turn 1: Spell Pierce that Thoughtseize. Turn 2: Mana Tithe that Kitesail Freebooter. Remainder of Turns: Win.
Which made me realize that the card I would most like to see reprinted in Masters 25 or Dominaria is one of your least favorites, Oversoul: Leyline of Sanctity. A deck running Sanctity + Mana Tithe is just strong shutdown for "I am going to ensure you never use your hand" strategies, which brings me joy. Aggro strategies can play right around that, so I guess my strong Naya biases are just my defining element, because I think that is totally fine. Spell Piercing Mana Leaks and Remands made me similarly happy, fwiw.
My only real problem, on returning to MtGO and looking at the metagame more broadly, is how much money one would have to spend to get the right solutions like Leyline of Sanctity. You were right, and I was wrong in context if not absolutely, about the price of Modern - building specific strategies that a reasonable casual player might want to play is crazy expensive. I built a Selesnya shell for four copies of Gaddock Teeg before realizing that the deck would cost me well over $100 due to his cost alone - a price for which I could build a half dozen decks, at the cost of those decks being less interesting or not precisely what I wanted to play. That is a real problem for the Modern format, and I see it now much more than before you wrote about it.