Solo Cassie poster for Quantumania!
It's been the worst part about the way they've been adapting the Young Avengers in the MCU. I wish they had gotten introduced as a team from the get go like in the comics so we could've had all the announcements at the same time instead of this waiting game.
That's not a good comparison because America was never Kate's girlfriend. Teddy actually IS Billy's boyfriend. That IS a part of his character story. America being some innocent, inexperienced girl who needs to be protected by Doctor Strange and become some sort of sorcerer's apprentice was not a part of her character story, and was not a good introduction to the character people actually loved in Young Avengers. That's the point I'm making here. If Teddy was to be introduced in a similar manner in The Marvels or Secret Invasion, I wouldn't have a reason to believe they're doing a good adaptation of the character I care about. Teddy being introduced as Billy's boyfriend wouldn't give me any reason to believe they don't understand the character, because again, that is a part of his story. I'm just saying that having a big role doesn't translate into having a good role, so I have no reason to believe him being introduced in TM/SI is inherently better than him being introduced in Coven Of Chaos.
To use another example: if America had a small role in the Loki show, teasing her meeting Kid Loki and their frenemy-like relationship that would eventually lead to them meeting the Young Avengers, that would've been 10x more exciting for me than what we got in Doctor Strange 2.
If it's too early to make assumptions about Captain America 4, then it's also too early to assume everything the Agatha show could or could not do. At the end of the day, we don't really know everything that's gonna happen. There are some threads from WandaVision that were left unanswered, like for example, who was the witness that Jimmy Woo was looking for. A lot of fans speculated that was Teddy at the time, specially with the casting call mentioning a male teen Skrull refugee needing protection from S.W.O.R.D.. So who knows? They could finally follow up on that. Him having a smaller, supporting role doesn't mean they can't do a proper set up for his cosmic story. It's pretty much what they did to Monica Rambeau in WandaVision.
For me, it doesn't really matter in which order they highlight things as long as they do it right. Not even the comics bothered to do that. Billy and Teddy were pretty much introduced as a package deal from their very first issue, and have been mostly together ever since, so them being introduced as a couple in the MCU is no more shocking than Mister Fantastic and Invisible Woman being introduced together. That's just the price you pay when a romantic relationship is such an intrinsic part of a character's story.