But this way around, store apps will always be viewed as the cheaper, less featured option.
If Microsoft wanted something competitive, they'd allow people to add other repositories to their stores, so manufactures could publish their own certs and people could chose to trust them .. remove MS from the middle man, but allow their update system to be more universal.
AFAIK, most major apps are on the macOS app store.
Even if your app can run in a sandbox today, are you willing to turn down any future feature requests that would make it so it won't?
We're putting an app on there, but our app is kind of an ideal use case because we don't expect to have to add features that can't work in the sandbox and our app is free. It's a tougher sell if you have to cut features to fit in the sandbox or hand off 30% of your sale to Apple.
Admittedly that 30% isn't unreasonable if you're really just starting out. That does include hosting, purchasing, and billing. But those things can be done at a much cheaper rate than 30% if you can set them up.
Panic is one of my favorite Mac app developers and (just checked) one of their apps (Coda) is distributed outside the App Store [1], while Transmit is distributed on both.
Office for Mac - https://www.microsoftstore.com/store/msusa/en_US/cat/Office-...
Adobe Acrobat Reader for Mac - https://helpx.adobe.com/acrobat/kb/install-reader-dc-mac-os....
What's CC?
Similarly, while you can get Photoshop Elements in the Windows Store, I don't believe you can get the full Photoshop CC on the Windows Store yet.
The Windows Store in contrast... most apps seem to be from a Microsoft contest a couple of years ago, where you could win a prize by writing a Metro app. The few decent apps can be counted on a hand and are all made by MS: Office Mobile (really good actually), Skype, Wunderlist/To-Do.