I think the best way to answer this is to first remember that its not a question whether the dialogue is suited for the supposed "target audience" or whether it was good to begin with, but how it compares to previous standards. Now its obvious that like any dub, there's the whole lip-flap matching thing that imposes limitations on how much freedom the scripters have to work with. That doesn't mean its going to be too unnatural most of the time, but it does force them to think carefully and be creative.
From the years of experience watching since OS, it definitely feels like there's less refinement put into the process of creating lines. It's like the dubbers write some drafts and decide between say, 2 possible lines instead of 5. Or when they need to squeeze in that extra few words they only use the very first thing that comes to mind, no matter if its just plain weird in context. (ex; Dawn saying something about "bushes rule!" after falling from a tree in a recent episode). Whether or not they're somehow trying to save time and/or are simply unskilled, I don't know. But I'm convinced that the standards, however they used to be, have indeed been lowered in the here and now.
It shouldn't be a question of "will the "target audience" care"?, it should be "why should today's audience have it any less than before"?