Coogler's company is doing the IronHeart show, IIRC, which is why she appeared in Wakanda Forever.
Iron Heart was totally a mcguffin in Wakanda Forever. She was the weakest part of the movie, IMO. She's getting a show because of Coogler.
Agatha and Echo, again, I'm clueless on why they are getting shows. I can name 20 characters that should get shows instead of these characters. Ditto Wonderman, but I think he's getting one because of the director.
That may be now, but is there really a reason why Agatha couldn't have been folded into VisionQuest?
I don't know about the actor salaries being such a big deal. That said, it's the budget / show constraints, especially since they are talking about cutting back, that make some of these choices questionable to me as a fan. If there's a limited number, then yes, I'd rather see something else chosen. That said, I trust Feige has his reasons and hope it will all come together and I see the characters I'm interested in before I die of old age.