Hmmm. I'd have to think about how this works with the structure of the series as is, and then compare what you're proposing to the series as it exists. Not a cop-out answer, but I'm going to need some time with this.
I've thought about this, and now I'm ready to respond.
Regarding stakes.
Season 1: If the Klingons win, Earth will be invaded/ravaged/devastated. Plus the whole "all life in the multiverse dying" thing floated by Stamets before they left the MU.
I disregard the whole "all life in the multiverse will die!" as the hyperbole it was. I thought of that for like two seconds and I've re-watched the first season countless times over the years. I keep my eye on the Klingon War. The threat of Earth being invaded works for me.
Season 2: If Control wins, all life in the galaxy will be ended by AI
It needed to be something serious enough to make Discovery leave the 23rd Century, so I was fine with it. In retrospect, the second season might've been a little bit ahead of its time, given how paranoid some people are about AI today.
Season 3: If Osyraa wins...uh...I guess the Federation doesn't get reborn? The Emerald Chain continues to be the major power of the quadrant?
Season 3 was interesting in that the travesty had already happened. The Burn was 120 years prior. The main thrusts of the end of S3 was to show why Burnham should be Captain and come up with a convincing reason for Saru to leave without killing him off or writing him out of the series. It wasn't about an escalating threat.
Season 4: If the DMA isn't turned off by Discovery, Earth gets destroyed inadvertently by Species 10-C
Disregarding Season 3, this was a mental escalation from Season 2, rather than a physical escalation. Control couldn't be reasoned with. Species 10-C could. The Klingons were stopped through the threat of force in S1. Control was stopped by being destroyed in S2. Species 10-C is reasoned with. Violence doesn't save the day, unlike in previous seasons.
Season 5: If the Breen get the progenitor tech...I dunno, I guess Starfleet HQ gets blown up?
No. You're looking at it completely the wrong way. It's not about the Breen. It's about the Progenitors. The Progenitors putting trust in Burnham's wisdom and abiding her decision. And she decides not to share Progenitor technology, knowing how easily it could fall into the wrong hands or how someone could do the wrong thing even with good intentions.
We see Michael grow as a character over time, and the crew work better together as a team. However, the level of threat, if anything, has decreased over time. There's also no evidence of more sophisticated and intelligent antagonists challenging our heroes as they learn from past stumbles. It's all just completely scattershot.
It's not scattershot. I just pointed out the trajectory above. Season 1 and 2 was an example of one way to solve problems. Season 4 and 5 were about a better way to solve problems. Season 3 was a breather where Burnham ascends to the Captaincy to make those choices in Season 4 and 5.
Imagine if, instead, we went from lower-level to more epic. Maybe in Season 1, Michael helps save a major starbase, playing a key role in settling the Klingon War.
That's an interesting idea for an episode, not a season.
Season 2, Michael helps uncover a clandestine effort by an evil AI to undermine Starfleet from the inside.
That works better for a season arc, but then there's no compelling reason to take Discovery out of the 23rd Century. The show stays a prequel, which it shouldn't be.
Season 3, she saves Earth.
Now it's a completely different series. Earth isn't part of the Federation in The Future. If it stays in The Past, then some overly-obsessed Canonistas would ask, "Why didn't we hear about this before?!" Which would lead to more Stupid Prequel Arguments. The best thing DSC ever did was get the Hell out of the 23rd Century. I hate, hate, hate, hate (can't emphasize this enough) Stupid Prequel Arguments and don't miss them in the slightest.
I also like novelty in The Future of Earth not being part of the Federation. I knew they'd have it rejoin eventually, but I liked the idea while it lasted.
Season 4, she saves the Federation as a whole
In a way, she basically already does this.
Season 5, she saves the galaxy. Then there would be a sense of forward movement, and her growing power as the protagonist.
Yes, but it also makes the series super-duper predictable. And what if the series had run seven seasons, instead of five? They didn't know the fifth season would be the last. Do you end with Burnham turning into a God?
No. I'm happy with how
Discovery unfolded as was. There are some tweaks I'd make, if I were in charge, but it sounds to me like you'd change the whole thing. I just think adjustments needed to be made. What you propose makes the series look drastically different and makes it stand out a lot less.
I don't want to get into this too much more. I already have one foot mentally out the door. So, I think we should just agree to disagree about the series as a whole. I want to change a few things, you want to change a lot of things. It's fine. It would be pretty boring if we all thought the same.