There are a number of reasons. I don’t live near enough to the trails I ride and like riding to them round a route and back. As the ride is mostly road to get there and there are a lot of bridleways en route the CX or gravle type bike appealed to me.
I commute on the kaffenback and would like to put discs on. So thought that I could use the Kaffenback to go exploring on too. The idea being that if I don’t like drops and skinny tyres off road then I still have a useable disced commuter. If the bug takes, then I can just swap the bits over to a new frame.