Which Season needed the full 26 episodes more? Season 3 or Season 4?
I feel like Season 3 would have been a lot better (perhaps the best season) if there had been a full season to explore the concepts that were ultimately rushed, such as Yumalia and Oropo's past. If we had 13 more episodes, we could have explored Oropo's stories far better than the OVAs. I believe Oropo had the potential to be the greatest villain in Wakfu (even surpassing Nox) if they had more time to plan things out (and remove the time loop nonsense). His story feels like a first draft when it could have been so much more.
Season 4 is in a similar boat, where they clearly wanted to do more ideas than they had the time to do. So they introduced the concepts (Flopin leaving, Inglorium empty, etc.) to be explained by future media. I think those ideas should have been saved for when they were actually going to tackle them. It just felt like an advertisement inside the actual show.
Admittedly, I'm not sure how much a full 26 episodes would have benefitted Toross. I think he's a fairly solid (albeit simplistic) villain that worked fairly well with the 13 episodes. Perhaps they could have explored how he got to that point of becoming a villain a bit more, or his relationship with the heroes.