You put your finger right on the issue. Having tried to subject myself on numerous occasions to listening to "modern rock 'n roll," I have come to the conclusion that all the talented song writers are either retired or dead. The stuff I have heard has no discernible melody or interesting rhythm, and it's invariably sung by untalented people who sound amazingly alike (generic male, generic female).
And all the reasons you enumerated are why I’m still listening to Iron Maiden.
Heavy metal genre, to be sure, but still far superior to what passes for “Top 40” these days.
And Bruce Dickinson is just an awesome human being. A modern polymath.
I call it angry music. They play the same droning 4 chords as hard as they can and you barely make out the words.
The problem? There's no longer a middle ground. It's either this cooler-than-thou "alt-rock" that leaves me totally cold, or the overcommercialized bubble gum. Similar to the movies -- dry, uberliberal "indies" and vapid sequels. Nothing seems to resonate or engage.