It's the de facto standard and the program you can assume everyone is already using, plus the fact that a lot of tooling relies on IDA (in part because, for a long time, it was the only game in town) for analysis and function recovery. I don't know if that really makes it "better".

I got out of this stuff before decompilation became a mainstream feature, so it might be a big deal that Ghidra has a strong decompiler.

Yeah, that's basically it. Most other tools either lack a decompiler or have a somewhat poorer one.