Why Thunderbolt 2 and not 3 on the Quantum Device and will it work with MAC Bootcamp in Windows?

Why on a brand new device are you not using the Thunderbolt 3 coector, now for any new computer (mac or windows) we need to buy an $85 adapter to use it?

If i do end up with this device, can i use it on a new MAC ruing windows Boot camp or only in OSX? (I plan to use both on the machine).