It seems that you're in the category of people who want to carry a keyboard and trackpad/mouse along with their iPad everywhere. I'm just not sure this category gather many people though. I may be wrong, but isn't the main use case of the iPad being touch interface + light + bigger screen than an iPhone? And keyboard and trackpad/mouse just being used at times under certain conditions? I mean generally speaking, not in your particular case.
If the vast majority of people wants to carry a keyboard + trackpad/mouse along with their iPad everywhere, then yes I'm more than willing to say that this new Magic keyboard accessory is a better fit than a separate keyboard + trackpad/mouse. But if that's not the case...
No, i want to carry around just the magic keyboard case and nothing else. I have the keyboard, built in trackpad and that’s it. I rarely take my iPad off my keyboard case when at work and i may take it off the odd time on the sofa but generally the iPad will stay on my magic keyboard. I have the touch when needed (with Apple Pencil for nav when i don’t want to use trackpad) but also the trackpad built in support to use it as a laptop replacement which it has been for a while now.
For other tasks that’s what my pro max is for.
Pro max and 12.9 with magic keyboard for me is the perfect combo and all i need.