>>28002848The GL is a continually updated feature that requires maintenance. You're still thinking of each game as a concrete unit, but they're increasingly becoming tied to internet services, which also require support and even some development staff for maintenance throughout the life of the product.
The Battle Frontier was only actually used and appreciated by a tiny niche of players and wasn't worth the development resources it required. It is unfortunate, because the Battle Frontier is fucking rad, but it's true.
I'm sorry if the 25 hour main campaign, extra Delta Episode, completing the Pokedex, legendary catching and Pokemon contests don't give you enough single player content for your primarily multiplayer oriented franchise.