I think that blaming Smalling and Jones makes people feel better (it's easy), as well as being a convenient way of shifting the blame away from the manager (if defending him is your priority).
Replacing them solves sod all.
@Bjerring suggests that replacing Smalling with another centre half will be "easy". Job's a good'un. What about that plonker from Sweden Mourinho bought for £30 million in the summer? I guess we could just play him instead if merely dropping Smalling will be the answer to the inability to score a goal at St James' Park.
I'm being facetious, but feck me, what a way to ignore the obvious and pin the blame on the easy targets.