DeNA has had difficulty keeping people playing Pokemon Masters - new content is cleared very quickly and beyond the top prizes from events (Candy, tickets, etc) most players quickly reach the point where lesser prizes (like the various Aids or skill capsules) become meaningless.
Compound this with many of the longer grinds, like EX stages for gear, already having been fully completed by many players and we have a genuine need for actual playable content with a reason to replay it.
So here’s egg pokemon: With a variety of moves, rarities and pokemon available there’s a huge amount of content to farm up…
But why even bother?
Every single egg pokemon lands with a resounding “Meh”. None of them compete with most top tier pokemon, to my knowledge, and yet all take considerably more work to be made useful.