The issue with mobile games houses is that they are all one-trick ponies. Rovio has utterly failed to monetize anything since AngryBirds and has been in slow decline, and recently laid off a whole load or staff. Zynga failed anything past farmville, etc.
Clash Of Clans (not King) and Candy Crush are the current "in thing", but they won't stay there, and what then? It's proven to be very hard to "make" a successful game - what becomes popular isn't necessarily what is technically or artistically good - it's just pot luck of the viral marketing from the user base.
This is true in "big games" that cost tens of millions to make, where there isn't actually all that much competition, let alone in mobile games where any one man show can put together a reasonable game if they can put together a decent icon set.
Fair play to the original owners - they are just doing the right thing and taking the money and running - but you have to wonder what the hell the purchasers are thinking ...