The JRPG (or as they used to be, simplified RPG) was never critical to the success of a console; it helped, but ultimately it was the presence of many and varied genres that made systems shine. The 360 has shown this to be quite true; it has many JRPGs, but is losing ground to the PS3 and has been in the Wii's shadow since the Wii's launch.
The original reason that the simplified RPG was so valuable to a console was for the very reason that most hardcore gamers hated them at the time they were invented: they made the RPG accessible to a whole new audience. Yes, the hardcore used to loathe the likes of Dragon Quest and Final Fantasy, seeing them as insults to the grand tradition of games like Ultima.
But as time went on, they stopped being simple. In pandering to fans, the genre segmented into many variations (action, strategy, themed, and many hybrids). The complexity kept going up and up, and the userbase kept dropping. This happens regularly in markets and sub-markets, of course (innovation -> growth -> segmentation -> decline -> crash). The origin of the simplified RPG's success was forgotten, and they were no longer simplified but rather just another form of complicated RPG with a distinctly Japanese air to them.
The RPG genre is in dire need of a new simplified entry. Dragon Quest games keep the flame burning, but a true innovation to change the genre and make it truly accessible will be necessary to save it from crashing.
Sky Render - Sanity is for the weak.
