Like control decks, midrange decks will gain incremental advantages over the course of the game, but where they differ is that midrange apply pressure to the opponent at all stages of the game, not just towards the end
It can protect valuable cards from black discard, and can combine with library shuffling effects to improve your draw (such as Thawing Glaciers, Flooded Strand, or Ramosian Sergeant)
Once worth over $40, its current price is much more manageable at $21.79, and its likely to drop more with this reprint
If the creature leaves play, it drops the equipment, becoming unattached and leaving the equipment behind on the battlefield
Despite this immense surge in sales, the price of Mirko hasnt spiked that hard just yet
I could go on about why these creatures are good in affinity but with the majority having been constructed staples in the deck I am sure there is more than enough literature out there already on why they are good