You definitely did the right thing. Isn't JAL premium economy a 2-4-2 configuration compared to 3-3-3 in regular economy? In this case, you can all sit together in a row of 4. Moreover, all seats have power outlets, whereas regular economy has shared power outlets. Lastly, you will enjoy leg rests, privacy foldouts, and seats in front of you don't recline into your space.

Someone correct me if any of the above info is wrong. It is what I remember reading when comparing JAL premium vs economy in the past.