Even though Hulk is already incredibly strong, putting on the armor certainly wouldn’t hurt.
There’s also a quick shot in the teaser trailer of the Hulkbuster armor landing and later fighting with the Mad Titan’s minions.
That being said, if that toy is indeed confirmation of what will go down in Avengers: Infinity War, then eventually Hulk will break free of the Hulkbuster and charge ahead without the added protection.
We know that Bruce Banner will meet up with Captain America, Black Widow, Black Panther and select other MCU heroes in Wakanda, and Banner will Hulk out so he can help fight Thanos’ horde of monsters.