Ok, so in looking over the rest of the mythics from Modern Horizons, these are the ones that stand out as being a) pushed, b) most likely to be played in multiples and c) capable of seeing play in both Modern and other formats
Each Play Booster contains 14 Magic: The Gathering cards and 1 Token/Ad card, Suspect Punchout card, or Art Card (Art Card found in 35% of packs)
It speaks to collectors who like premium packaging, physical extras, and display-worthy releases that feel tied to a specific moment in franchise history
Third, it's possible that Wizards knows that the London mulligan rule has potential to be harmful to Modern but has a plan in place to fix the problem, either with aggressive bannings or with the help of new cards coming in Modern Horizons (one long-shot theory is that Force of Will will show up in Modern Horizons , which would suddenly make Modern much more like Legacy and give decks a free answer to degenerate, fast combos)
there are literally hundreds going on all the time around the world