Because let’s face it. Without Coulson, this becomes a very different show. I’ll happily watch this new show, but Clark Gregg’s Coulson was one of the most effortly confident performances on any of the shows I watch. He was the solid center of the show, with only Ming Na-Wen coming close.
They killed Fitz too, but reminded us that they have a spare - the cryogenically frozen Fitz waiting out in space for the future that will never come. Which is gloriously clever. Deke’s fate is unknown, presumably intentionally, so they can decide whether he’s necessary for Season 6. I don’t think he is, but he’s available if they want him - wandering the world and either blinking out of existence or not depending on how the show decides time works.
Mack’s the new Director of SHIELD, which is debatable. Not because of the character, but because of the reasoning - that he’s somehow SHIELD’s “moral center”, which isn’t really a thing he’s demonstrated until this season, when all the other characters did something slightly shady and pissed him off. But it’s fine.
The ultimate solution to the Graviton problem ended up being giving the Centipede Serum (healing version) to Daisy to amp up her powers and let her launch Talbot into orbit, killing him quickly and efficiently and safely. Fun little fight scene, with them opting to spend more money on two or three big shots instead of spreading it out over a bigger, longer fight.
All in all, a very satifsying conclusion to a pretty successful season. Not my favorite, but up there with the better ones.