Interesting point. I never have the tv on like this (in fact it winds me up when it's on and no-one is watching it) instead I sit down and watch it. But I see your point - in fact, it nicely illustrates what I thought was wrong with the current series; it never did demand your full attention since the plots were so light. Early series (particularly the Matt Smith run) needed closer attention.
Of course, some prefer the current version (as seen, arguably, by the audience figures) but not this viewer.