As someone who grinds the double trainer battle for like 140,000$ per match (or something ridiculous) I can just do that battle 5 times and buy 35ish rare candys, Instant levels to level 80 pokemon.
It makes late game grinding more or less nonexistent if you can beat a trainer for infinite amounts of pokedollars, For the early game it made sense for us to struggle but once you're about 2/3 through the game you're at the point where the grind is unnecessary.
Infinite $$$ is a problem, but it just makes the inevitable easier and saves you some time (That Alt 3x speed thing is easily the best new feature though)