Well, most countries can't easily get air superiority.
Plus, some countries don't support the idea of choppers, some don't even have proper ground attack planes.
150mm gun? You are kidding........ You don't need that to knock out a tank......
For the type 98(in comparison to the Leclerc), the chassis is OK, it was owned by the T-72, and has the mobility and speed, at 65 km/h, as provided by the 1200/1500 hp engine.
The gun is OK, but the armor is rather bad. It had a gap in the 98, and had to rely on ERA(not good) on the 99. I doubt its armor is as good as the others.
For the FCS, it's most definitely worse than those of Leclerc.