For a camera that you carry everywhere with you, being weather proofed is a big advantage. You will have one less thing to worry about. Large Full frame (35.9 x 23.9 mm) sensor
Large sensor in Nikon D780 ensures a good low light image quality compared to smaller sensor, and it also provide shallow depth of field and a nice blurry background when needed.
Even the smallest lens attached to this body will be a burden to carry everywhere with you. 840g
Carrying this weight all day may not be very comfortable for you. Body Thickness 76mm
With a thickness of 76mm,Nikon D780 is not a pocketable camera for sure.