There’s FreeBSD in almost every data centre. But it’s at a level most application developers just never see. Many infrastructure elements - from storage heads, to core routers, to enterprise application and security appliances - have chosen FreeBSD as the high quality, reliable, consistent, and liberally licensed base for their control plane software.
The point being, this is where FreeBSD has the greatest influence and adoption: as a platform, not the product, and not at all obvious even to those that thereby rely upon it.
That being said, yes it works great as the instance OS in EC2 and as a die-hard acolyte since 2.1-RELEASE you’ll pry my production application jails from my cold dead hands