Ni No Kuni seemed like good aspirational comparison, obviously the market wasn't there though. It played heavy to all-ages and nostalgic themes, it was a collaboration with Ghibli, even it's visual style and game design evoked DQ on some levels. The PS3 version wasn't a port either, it was an entirely new game that retold the DS version's story and added quite a bit more to it.I was using install base to show why a big userbase doesn't neccessary means the JRPG demo will be there even if a big JRPG exist on it, eg. Pokemon.
DQX wasn't a failure on the Wii, but because there was so many ports, which would lower profits just because of the cost to do so, would have made SE think twice about where DQ will go. I think they rather minimize the number of ports as much as possible. I don't think Ninokuni is a good example because it was released on the DS first, the PS3 was a late port. IIRC the DS version didn't perform very well either, it was overshipped and took awhile to sell its initial shipment.
In terms if demographics I think you're just underselling Dragon Quest. It just has a far wider reach than most JRPGs. Something like Tales is incredibly narrow in comparison in terms of target demographics. What you should be looking at are properties from Nintendo, Ghibli or Disney. The target is "everyone". Even Pokémon is probably a closer match than Tales.