Birth defects are forever. If the design has a problem, "small diffs" won't fix it. That's the trouble with the "continuous hacking and integration" approach.
I think that's a bit too fatalist. I'd hate to have an org fall into the trap of "oh, well I guess since we didn't plan for changes since the beginning, we're stuck with 21 point stories and appropriately long 4 week sprints". I want to hope that the outcome of this post is "hey, I wonder if I can ship smaller parts of this to make the whole less risky"