For the first time in over a month i got a chance to sit down with a buddy and play KI today. We had the single best match of our lives, and then discovered that we couldnt re-watch it because we were not connected to XBL 
I dont know how hard it is to create an offline replay function, but if it could be done, i vote that it should.
Not sure how many people also play local offline, so i may be part of a small minority, but if it is actually a big deal to others, then please let the devs know and post about it.