I loved walking-Pokémon feature, and was very disappointed to see it gone.
Although Pokémon are meant to remain within our Poké Balls inside our backpack (after all, they are referred to as Pocket Monsters in Japan), but even so, they are also encouraged to be treated as friends and whatnot; we hang around with them, accompany them, etc. By putting these kind of thoughts into consideration, I do believe it makes sense to have such a system around.
If they do re-implement following-Pokémon, perhaps one thing they could improve is maybe give us option to choose which teammate we want walking beside ourselves, rather than only first member of our party?