How extreme is it, really? It’s a JRPG built very much around combat, level-grinding, notable difficulty boosts, and iterative repetition of dungeons. That does make it an extreme version of traditional JRPG gameplay, but being so combat-focused also makes it very light on story. Thus it's an extreme version of only 50% of the format. In purely mathematical terms, that means it breaks even at 'normal, non-extreme JRPG'.
How could it be made truly extreme? By making it the complete extreme JRPG experience. All Grandia, all the time, cranked up to a level that will make your head spin. Constant, ultra-hard combat coupled with the most talkative, emotive party characters and enemies in any game ever, conducting hundreds of thousands of lines of interactive dialogue during every moment of the game. Juggle fights while perpetually navigating deep, layered, exposition-filled conversation or lose track of absolutely anything that might be going on. And then die.