If IAR was able to make the existing C++ codebase fit in the chip's flash and GCC wasn't, that seems like a win for IAR. If you're selling products in volume, the cost of the IAR license is dwarfed by the amount of money you save by using a part with less flash.
Depends on what volume means. I would argue most people aren't working on projects in the million of units volume where that cost savings isn't worth it.
Lots of people are. It's usually small systems. Think PIC or RL78, 16 bit MCU's maybe some Cortex M. But they're everywhere and sold in the millions and you never even think about it unless something goes wrong and then you cuss at them.
