While I agree music on TNG definitely took a downward spiral, and indeed much of the franchise is really lacking in the episodic music department. In Voyager's last few seasons they did get some pretty decent music in their action scenes, though admittedly this suffered a bit from overuse. Enterprise, while not exactly memorable, its music did tend to be somewhat livelier than the single bland note that characterized much of the episodic music during Berman's reign.
When McCarthy and Chattaway were the only regular composers working TNG/DS9 simultaneously you could feel their work being stretched thin. The music really got noticeably better once Berman started hiring more composers like David Bell, Paul Baillargeon, and Kevin Kiner in the rotation, which had a really positive impact on McCarthy and Chattway's work post-TNG. Makes me wonder why Berman didn't just do more of that during the TNG years. More composers brought more variety.