Here's why:
* Nintendo hasn't announced any plans: There's been no official word from Nintendo or Game Freak about bringing back the feature.
* Hidden Grottos were specific to Gen 4: The Hidden Grottos were a feature exclusive to Pokémon Diamond, Pearl, and Platinum. They haven't appeared in any other game.
* Game design choices: Game developers constantly experiment with new features and mechanics. It's possible they have other ideas for generating encounters or rare Pokémon that they prefer over Hidden Grottos.
However, there are some arguments for their potential return:
* Popularity: Hidden Grottos were a popular feature, allowing players to find rare Pokémon in a more engaging way than random encounters.
* Nostalgia: Fans of the Gen 4 games often fondly remember the excitement of discovering hidden Pokémon.
* Remakes: If Pokémon Diamond and Pearl receive another remake, it's conceivable that Hidden Grottos could be included as a throwback feature.
Ultimately, the future of Hidden Grottos is uncertain. It's best to stay tuned for any official announcements from Nintendo and Game Freak.