Posting my thoughts originally posted mistakenly in the FRLG topic...
Arguably, Sevii DID detract focus from Kanto itself. The Kanto of FRLG was quite dull, largely being identical to the Kanto from the original games apart from updated tilesets. I'm not arguing that this was because of Sevii (Game Freak probably just hadn't decided how many liberties to allow themselves to take with the original games at that point), but the Sevii Islands did seem to be added in part to provide the largely flat and featureless Kanto region some much needed geographic diversity (and the biodiversity that came with it), including such locations as a volcano, ice cave, and ruins. But Hoenn already has a much more impressive volcano and plenty of ruins, and while only the deepest parts of Shoal Cave would qualify as an ice cave, I'd much rather Game Freak expand that cave than devote resources to including all of the Sevii Islands, since so much of them would be so redundant.
I suppose there would be benefits to bringing the Sevii Islands back, especially making Unown available again, since it has been unobtainable without transferring since Generation IV. But ultimately I'd prefer older Pokémon to be integrated into existing Hoenn locations, whether by expanding the Hoenn Dex or by making them available in the postgame through swarms or other means.
I really don't understand the logic of people saying that the Sevii Islands or a similar postgame area would detract from Hoenn and "take focus away from it". Hoenn is going to be in this game regardless of whether Sevii Islands is in or not. You might as well argue Sevii detracted focus from Kanto itself.
Arguably, Sevii DID detract focus from Kanto itself. The Kanto of FRLG was quite dull, largely being identical to the Kanto from the original games apart from updated tilesets. I'm not arguing that this was because of Sevii (Game Freak probably just hadn't decided how many liberties to allow themselves to take with the original games at that point), but the Sevii Islands did seem to be added in part to provide the largely flat and featureless Kanto region some much needed geographic diversity (and the biodiversity that came with it), including such locations as a volcano, ice cave, and ruins. But Hoenn already has a much more impressive volcano and plenty of ruins, and while only the deepest parts of Shoal Cave would qualify as an ice cave, I'd much rather Game Freak expand that cave than devote resources to including all of the Sevii Islands, since so much of them would be so redundant.
I suppose there would be benefits to bringing the Sevii Islands back, especially making Unown available again, since it has been unobtainable without transferring since Generation IV. But ultimately I'd prefer older Pokémon to be integrated into existing Hoenn locations, whether by expanding the Hoenn Dex or by making them available in the postgame through swarms or other means.