From what I heard they didn't develop completely independently. Yuji Horii loved Wizardry and wanted to make a more accessible version of the game that anybody could play. From that point on, everyone in Japan was trying to reimagine Dragon Quest, a lot of them probably had no idea what Wizardry was. There were JRPGs before DQ, but that was the game that established the archetype, the rules by which everyone else had to follow.

I haven't played the classics yet, but one strength of WRPGs is that they're always about letting you create your own characters from the start. This gives you a good sense of control, feeling like you're experiencing a totally different game than someone else who may have made a different character. Of course, the counter to this is that JRPGs do a great job of letting you customize your character over time and make them completely different than anyone else's.

What really separates the two is the legitimate freedom of choice in WRPGs. If you don't feel like setting off quite yet to that distant town where the next chapter of the story takes place, there's plenty of things around you right now to get busy on. I've found most JRPGs stockpile their sidequests on the back end.

Accordingly, the strength of the JRPG is its ability to create the set piece. It's that moment when you're in a specific area, with a specific objective in mind, a song is playing that was especially crafted for that sequence, there's tons of crazy things going on around you, and this moment has paramount consequences to the story. In the newer WRPGs I've played everything seems kind of stiff and static to me. I can choose to go off and explore a dungeon, but that dungeon will always be waiting for me. It will always look the same, sound the same, it will generally have the same placement of traps and layout of enemies, even if the types of monsters changes as I increase in level. However, that JRPG moment will never exist again in the story, it's a one time thing, and it's completely different from anything else you'll see in the story.

It all comes down to crafting an experience to letting the player make one for themselves. I think it's a harder endeavor to create a story, with visuals, writing, and music that all work together to make the player feel something. I'm enjoying Oblivion, but all too often I find I'm in a boring town with boring NPCs and I'm responsible for going out and making my own fun. I know there's older games you guys recommend in the genre but I can't imagine how other high fantasy takes could make such towns any more interesting.

That's another topic in the debate. I've noticed all the WRPGs I've been exposed to stick to either the high fantasy or sci fi setting. JRPGs break the boundaries of these genre more, such as fighting robots and activating computers in Final Fantasy I's Wind Temple or slaying dragons near the Nibehlheim reactor in Final Fantasy VII. The SMT games and Valkyria Chronicles are also interesting examples of how Japan deviates from generic Fantasy/Sci Fi settings.

JRPGs also have a pretty successful subgenres, like SRPGs which have distinctive game design from the traditional game. I know there's rogue-likes and action-oriented games, but I haven't seen a lot of differentiation or variation in WRPGs aside from some being in first person as one character and others in third person with a party.

I know this post came off as more fanboyish than I would've liked, but those are a couple of the differences I've seen based on my current foray into WRPGs.