My impression from being in the industry far too long is that Bluetooth was one of a variety of what I think were being touted as personal area (wireless) networks once upon a time with Bluetooth seemingly being pushed for relatively simple use cases like keyboards. But none of those other protocols panned out so Bluetooth ended up being the general non-WiFi wireless standard for things that the original spec never contemplated. The standard has been updated over time of course but I imagine a lot of early-on decisions still have an impact on things.