Can't you see? There's no reason they should butcher Sinnoh's world design to fit the likes of Alola and Galar.
LGPE was the most open Pokemon has ever been. It's not a bad thing if they focus on polishing Sinnoh with this treatment. Would you really rather have them go against their principles and shove a regional gimmick in the remakes, only to further lock down the game so that you're just walking from checkpoint to checkpoint?

If you ever enjoyed the older Pokemon games. You take the Let's GO/Sleep pill. It's a sad truth, but if you don't give this remake a good reception then GameFreak will only get the idea that gameplay = bad.