We all have decks that are linear, or a little fragile to interaction, but that we love
You have access to a host of combos with cards like Mirran Spy and Chakram Retriever, not to mention whatever nonsense you get up to with cards like Urza, Lord High Artificer and Displacer Kitten
Dont get me wrong, Miles will still be quite strong, but the back half is a beater, especially if you transform it after you already put a +1/+1 counter on it with Miles
Half of the time, the card in this slot is the global version of a Mystical Archive card, and the other half of the time, it's the Japanese alternate-art version of a Mystical Archive card
On top of that, you get a big body that can bring you back from the brink, and it can also help you close out the game quickly