The arc of S2 was "Della is so cool, look at how cool she is. She's so much cooler than all the other characters Also something something Darkwing"
There are several plot arcs in each of the seasons and S2 was Louie’s season, with him learning Scrooge is the ideal mentor figure for him and Scrooge learning... something. That plot was kinda a weird mess in a way that I wonder how much there was rewriting... In any case it’s the plot that interests me the most ‘RE: what is the genuine ideology of this show?’
Personally I don’t have a massive issue with Della. The show kinda has an issue with Strong Female Characters but Della was more well rounded than I expected based on the show’s track record and it sure handled her disability better than I dared to hope (again based on past track record)
The show in general has the issue of the cast being hugely bloated so almost no one has enough screen time so I don’t know if I would point at Della as the problem, they had to dedicate screentime to establish her... I have plenty of issues with the handling of the Della mystery though and one can have different opinions on whether the show should have tackled ‘what happened to HDL’s mum?’ at all of course
I think Donald is treated terribly by the show and sidelined as the father figure but I don’t think that’s an issue with Della being brought back, it’s how much Scrooge is a father figure for not only to HDL but for Donald and Della too
Della is back in the family dynamic and she looks up to Scrooge in a way and makes Donald be the responsible parent (but of course the show is weird with danger so... Donald is just wrong in worrying) that it feels like she isn’t really an adult? In the end it’s Scrooge who is the ‘parent’
Donald being sidelined really makes Della suffer as a character too imo