I hear that. When I play Japan the only defensive thing I do is put 1-2 infantry onto Japan proper each turn. Other than that every action I take is some sort of offense.
The problem we’ve found playing Japan in Global is not that it can’t gain territory and resources quickly (although, bringing the US into the war early
is a problem, given how aggressive it always is in the Pacific). The problem is largely that Japan is outnumbered 5 turns to 1 in the theater (and, unlike Germany/Italy, Japan will never have a can-opener option in the theater).
That, and the short pipeline from West Coast US to Australia (and from there, the money islands, or other strategic locations) via naval bases.
Add to that the fact that (in our experience) US can afford to throw carriers in the Pacific (many of which ANZAC can load) while still maintaining a supporting presence in the other hemisphere.
(Fun fact: ANZAC or UK fighters that are loaded on US carriers effectively gain a range of +2 seazones over the course of the round, assuming the carriers move.)
And the subs! A constant supply of US subs will choke Japan’s economy every time! Especially keeping in mind that the money islands are right along that naval-base pipeline I mentioned earlier.
Edited to add: The convoys are actually another major problem for Japan. It is the only power whose resources (both starting and through conquest) are almost completely subject to convoy raids. And no matter how well they’re doing, building one sacrificial sub-hunting destroyer for every submarine-group that USA spreads across the map is not a war of attrition they can win. Not to mention that sub-hunting also ties up their air-force which might otherwise be used to take territory or attack fleets.