A lot of JRPGs seem to have world maps that look primarily like archipelagos, with long thin peninsulas and lots of small islands. I wonder if this is because creators are inspired by their area of the world, Asia, which is most similar to this design. Just really quickly let's go through Final Fantasy.
Look at FF4:
http://www.finalfantasykingdom.net/4/overworld.jpg
On the right, an archipelago, and every island has extensive spidery peninsulas, with very little land density.
Final Fantasy 5:
http://www.finalfantasykingdom.net/5/map1.png
Again, mostly thin long peninsulas and an archipelago in the bottom right
Final Fantasy 6:
http://www.uffsite.net/ff6/images/maps/1.jpg
Closer to continental land masses, but still look at the finger-like peninsulas.
FF7:
http://www.finalfantasykingdom.net/7/map1.png
Still with the fingery peninsulas and spidery bays
FF9:
http://www.ffwa.eu/ff9/images/worldmap.jpg
One main continent and a bunch of long thin islands and fingery peninsulas.
FF10:
http://www.ffshrine.org/ffx/ffxmap.jpg
This is just explicitly a take on Japan.