DQ8 was my RPG of the PS2 era, and only the sheer lunacy of Shadow Hearts: Covenant comes close.
DQ9 was way more disappointing than most reviewers claimed, filled with archaic design decisions. Not to the game as a whole, but the modern stuff they added. "You can only hold 10 quests at a time, but we'll give you endgame quests in the first main town eating up slots with no way to know better." "Go kill some salamanders in the random dungeons... except your level is too high, so the odds of the RNG spitting out a dungeon with salamanders in it is like 1/100, and the only way to get more dungeons is to waste your time doing trivially easy dungeons over and over." "You can make your entire party look like anything you want... which means that your characters have no personality, and no quest can reference anything about them (since the designers don't know anything ahead of time). So instead of a silent protagonist, you have a silent party, with the bad guy not introduced until 3/4ths through the game, and defeated by a ghost introduced 7/8ths into the game."
DQ10 I didn't play, because there are too many English-speaking MMOs to go through.
Obviously, I'm hoping this is more like 8. And yeah, the platforms are interesting. DQ has always gone to the platform with the most systems in Japan... but since this isn't going to phones, S/E just decided to send it to every system that'll be alive in Japan then. Sadly, the NX bit doesn't tell us anything about it, as circumstantial evidence suggests "it" is both a new handheld AND a new console system, with most/all games buyable (separately*) on both consoles.
*I can't wait for people to use Club Nintendo 2 points to get discounts for cross buys in about 5 years or so.