>However, since this is not a widespread practice so far, (almost) nobody has complained about it.
You haven't seen people complain about Twilight, or Fifty Shades of Grey?
You haven't seen people complain about Twilight, or Fifty Shades of Grey?
Now the same author may churn out book after book which seem pretty repetitive, but that may be because it's their own style. That is, their works may certainly be formulaic, but at least it's their own formula.
So what I meant by the comparison with pop music is, the criticism is not just that the same artist puts out albums that sound like their previous ones, but rather that all artists start to sound like each other. And that is what I fear may happen with "pop lit": in the quest to appeal to as wide an audience as possible, all authors may end up sounding like each other.