It was poor writing. Pure and simple, they didn't take the time or make the effort to iron out the kinks in the script. I said it before, but the solution was already in the movie, but they didn't see it. She dreams into the multiverse and sees that there are versions of her children in actual danger (not just happy family-time). However, the Darkhold is twisting her nightmares, pushing her to take action, draw on more power. She dreamwalks to other parallel worlds to try and save them, but fails over and over as her powers are limited, and she finds a solution in America Chavez.
Strange in turn is confronted with his hubris, as the man who knows what to do, the man with the plan. His actions in Earth 616 led to countless deaths in the ensuing chaos following the snap. Additionally, the barrier between realities has thinned as a consequence of NWH (and Loki), causing Wanda to dream of the multiverse. We learn that Strange variants have destroyed other realities, like in the movie, and we explore what this shared multiversal thread that pushes Strange to be a hero is, is he just a good man or is he willing to do whatever it takes to protect the people he loves, to save Christine?
This centers the conflict on both Wanda and Strange. How far are they willing to go to save the 'World' or the people they care about. The trauma that Wanda experiences becomes more intense and is grounded in something 'real' as she isn't trying to kidnap happy versions of her kids, but save them from the common threat within an infinite amount of universes, Dr. Strange. How is he any less a monster for the choices he's made. That could have been a compelling narrative for Stephen and positioned him and Wanda as tragic foils to the other. Sadly, with the films efforts to not tarnish Strange in any way, they actually settled on not giving him a story at all.
Position the Illuminati as leaders of a corrupt Utopia. Aware of the ensuing threat of incursions and actively sacrificing other universes to preserve their own. But why bother with compelling narrative and effectual villains, why parallel the perspectives of your leads and villains in a manner that ties the story together in a cohesive manner. Just call them cameos and save the story for some other movie.