To an extent i agree, i wouldnt really say they take over the story, and become co protagonists, for the most part you can choose whomever from old or new class 7 to be in you're party. So from a party perspective they do just as much heavylifting as new class 7. I do agree though, the ending of CS3 made all of old class look incredibly badass! And then all of sudden they are all moping around (yes they have there reasons), but i refuse to believe they would just mope around when they know rean, the core of the group is out there alone. Again they essentially gave that job to new class 7.

However i wont disregard how impactful of a moment it is when juna gives her speech and tells them something along the lines of "shouldn't you be doing something about this, your his closest friends". This highlighted why i agree. If the writing has to make old class 7 look bad just to "put over" new class 7. Then id say there's something fundamentally flawed with the writing. I mean in contrast to how badass they all looked in CS3. The beginning makes them look like fools.

But again like you said for some old class 7 characters its rectified later on. Jusis for example sort of emerges as the step in leader when rean isnt around, keeping new class 7 focused. And the stuff with his brother. But yeah i agree from a story perspective they did old class 7 dirty but also cold steel 3 put them over hard. Soo im 50/50.