One thing that I think has been overlooked here. certain rhythms are considered "modern" or "dated." Current trends in contemporary music have lately been using a particular rhythm throughout the melody. I believe this to be true for modern songs of all genres, but different rhythms from genre to genre.
the rhythms I'm speaking of are just small phrases included usually in the chorus, sometimes once, sometimes more than once (with that same rhythm). just about 4 notes (in an example) with a particular pattern to the rhythm of that phrase.
the rhythms can have any particular melody, but they might follow a particular melodic pattern in reference to the beginning note of that phrase. for example, a pattern might be dotted 8th, 8th, 8th, dotted 8th with a melodic pattern of an initial pitch, 1/2 step up, another 1/2 step up, back to initial pitch (this is a made up example and does not convey any particular genre's modern pattern).
I know that modern Contemporary Christian Music has these "modern patterns" and I believe that it is probably true for all modern genres, but I haven't studied them to find out what those patterns might be.
this might be what the reviewers are looking for - and they might not even know that this is what they're looking for - they just don't "hear" it and therefore they think it's not "modern."