Hello subechin, and welcome to FT and AY+ Forum! For me Platinum is much better than Gold.
1) You can gift Gold card.
2) More upgrade vouchers and 50,000 point upgrade for long-haul r/t.
3) First lounges are usually much nicer than business class lounges. (I don't know about KIX.)
4) FAs treat you better (works at least on AY, CX, AA, JL), they know your status.
As for getting it, remember that you can exchange award points 3:1 to status points.