Microtransactions are way older than 15 years. Wizards of the Coast was selling randomized MtG booster packs in 1993. I'm guessing that the earliest loot boxes for kids were baseball card packs, with very similar psychological purpose to today's game cosmetic collectibles.
Baseball card packs are an innovation. If you read Peanuts, you'll see that they're referred to as "bubble gum cards", because cards were included as promotional items in packs of gum, a "free toy inside" that was compatible with the size and shape of bubble gum. They moved to dedicated packs of cards when people started buying gum to get the cards.
A physical photo in my hand is sooo limited compared to the same photo in my hand via the screen on my smartphone. Same with a DVD or CD or Disc - all antiquated tech.