That -could- have been really cool, yes. But also a lot of classes just don't -have- a bonus action for most turns. Clerics can Healing Word as a bonus action but that's about it. You really have to settle in on doing options for every class in that kinda structure. Not that I think it'd be 'too much work' or a bad idea, or anything. Just that it isn't some big money-centric design decision that WotC forced on their employees as a core design principle they couldn't get rid of.
But here's a new question:
What kind of Setting would best allow this kind of dramatic game redesign?
My first instinct is to go to the old favorite: High Fantasy.
Being able to cast multiple high level spells every encounter just feels like High Fantasy. It's the kind of mythical stuff Forgotten Realms are built from. Specifically trying to cover all the 'classic fantasy' power sources, too, feels very high fantasy. Granted, pacing things out a little more slowly, baking in some nonmagical in-combat recovery, and reducing attrition rates to mostly swirl around hit points rather than direct throughput does lend itself fairly well to low-fantasy settings.
But in either case, what are you really offering on the cover of the book, which most people judge material by well in advance of purchase regardless of what platitudes they appreciate? You don't have a lot of space in the title to explain what makes your product different, after all. (Even with my long as hell subtitles for everything I've put out, so far). So you have to convey it with artwork to stand out a bit, and a setting that isn't heavily marketed so there's something at least marginally different about your book to draw attention.
So you've gotta be at least a -little- different from Standard Fare.
You -could- play into Nostalgia.
It's incredibly common to do so, in general, these days, because of the lack of any unifying experience. After all, that's why Weird Al Yankovich stopped making parody songs. After a while, the music industry had expanded far enough that there's no longer any "Everyone knows it" songs. Back in the 80s, Michael Jackson was the hottest possible thing, with Madonna right beside him. You could parody either of their materials and the majority of the populace would know what you were parodying and find it fun.
Now? It's not an option. And without the unifying experience, you're just SoL. Mandatory Fun was probably his last album of parody songs, ever.
It's the same reason movies studios and the like have spent the past 20 years or so diving as hard as possible into Nostalgia. They're reaching back in time to the "Big Hits" for remakes and reprisals so the wide audience appeal that -used- to exist can be tapped into in order to make films that appeal to the widest possible audience. That's why Robocop, Total Recall, Teenage Mutant Ninja Turtles, Thundercats, He-Man, My Little Pony, She-Ra, and more are seeing a resurgence...
But the cartoons are still largely aimed at kids who have no connection to the original in hopes their parents will sit down and watch with the family. Which, of course, ignores modern family dynamics entirely with most everyone online in different rooms of the house at any given moment or being in the same room on your phone occasionally asking the other person to share whatever just made them giggle. The best performing cartoons of which, by the way, aimed themselves directly at the underserved little and tween girl audiences and became massive hits even among grown men.
So... maybe a Nostalgia pitch. I did write up that rough outline of the Science-Fantasy "Aliens invaded a high fantasy setting!" idea based on pulling an MST3K on Krull with my husband.
Could get art specifically meant to look like a modern version of those 1980s animated TV series like the Mythforce videogame which kinda looks rotoscoped and kinda looks like Pirates of Darkwater and kinda looks like He-Man.
Bonus Points for your audience: There's a massive amount of tutorials and 'how to draw' books that touch on these kinds of art styles.
Could also aim for something more stylized like modern cartoons in the vein of Dimension 20's art for Fantasy High. Won't quite hit the nostalgia button for your over-50s as hard, but your younger millennials and gen Z fans will have a stronger connection to it thanks to it being a prominent style of their childhood in the late 90s, early 2000s.
Personally, I lean more toward Mythforce, but that might be my biases as someone who grew up in the 80s.
What kinds of settings and art styles do you think would work best for something this dramatic?
