I actually didn't think it was as bad as most people usually do (I hated the overuse of nukes and using a giant orbiting memorial as a Colony Drop more than anything else). And Cagalli was head stong and didn't take any crap in Gundam Seed, and she was a very good pilot (and as pointed out, the only regular human to get Seed Mode). However it seemed like all she did in Gundam Seed Destiny was cry over being helpless to change anything and otherwise useless....until they broke out the Akatsuki. She finally gets the chance to pilot a machine the same caliber as Kira and Athrun's Gundams.....and she gives it away (admittedly she gave it to Mu La Flaga, so it's not like it wasn't in capable hands, but still her father built the thing). Between telling Durandal to take his Destiny Plan and shove it and piloting that thing, it looked like she was close to being her old self again....only to wind up not being involved in the rest of the series. Now admittedly she was the only one left who knew how to keep Orb from falling apart after some of the leadership tried to screw the nation over, but it seemed like they were out to get her in this series. It's a shame her seiyuu won't do the role anymore, even for the video games. I think most of the games have tried to actually undo the derailment, or at the very least you can make her do some awesome things in games where you can stick her in any MS you wish.

There actually was a Seed movie planned, but one of the writers got sick so it's totally stalled. Considering Naomi Shindo won't do Cagalli anymore, and there was varied animosity from some other people who did the series, I doubt it will ever happen. It would probably help if they replaced the writers so that some of the damage can be canonly undone, but I think people are too focused on 00 and Unicorn to care anymore.