I couldn't find a scenario where Wi-Fi would add value as opposed to BLE. It consumes more power, forces you to use TCP/IP, which pulls in lots of complexity without great solutions (you need to deal with pairing, security, etc), is more complex to set up... I could go on. Solutions like Thread are relatively recent (in fact I still don't know if licensing has become more reasonable).

BLE and Bluetooth Mesh give you tons of functionality with low power, in a complete solution. Do I really need my devices to have an IP address?

I guess this depends on what you're building, but in most cases this is about home automation, sensors, lighting, toys, etc.