It's funny that you chose this one as an example of a typical town theme, especially since it contains some elements like synthesized drum beats that usually are not found in town themes in JRPGs. Especially the beginning part gives me more of a "Save Screen" vibe than a town. Later on, the peaceful melody and selection of harmonies and melodic lines clearly is more "peaceful town", but still I think for example Kakariko Village from Zelda: A Link to the Past is a better example of stereotypical "town themes".
I think the main aspect of JRPG town themes is that there is no sense of threat audible in the music. The songs are usually downtempo, have some beautiful melodies played on serene, soothing instruments. They often have some kind of strings/pads for the chords to create a warm, welcoming atmosphere, and the chords are predominantly major ones. When there are too many minor chords in there it mutates more into a love/sadness theme, so the major chords play a major role here (no pun intended
Instrumentation is also a very important aspect, as town themes usually have little to no percussion in them. If anything, it's some light stuff like shakers or tambourines. There are of course examples like Secret of Mana's town theme, but that one also has a very happy vibe to it because of its jumpy melody and cute instrumentation. Generally the instruments are non-threatening in nature. Harsh sounds like electric guitars, heavy drums or deep basses/brass are usually left out to create a more natural, soft mood that doesn't feel too dramatic.
The song structure is also usually more predictable, so the player gets the feeling they know the place and there will be no surprises, and they can feel right at home without fearing any threatening dangers or battles.
I think those are the main ingredients to create a typical JRPG town theme that fits into all those classic games.