There are so many advantages to using Mac App Store.
• I don't need to worry about some app stealing my private files or similar.
• If it isn't good, I can leave a review that the author probably reads and cares about.
• I don't have to hunt for executables and make sure I have the license file in my mailbox whenever I want to use my copy on one of my other machines.
This is highly unlikely. But I estimate a probability of 0.7 that you don't have notable security protecting your computer and your top secret files, even though your machine is on the net.
> If it isn't good, I can leave a review that the author probably reads and cares about
Most (any decent) 3rd party software developers have some kind of feedback channel.
That said, by default I generally find apps via recommendations, random packaged deals, or via their website so I don't necessarily "go looking" for them in the Mac App Store either. All of the above mentioned apps that I found that were App Store only falls into this category.
If there is an option for both (App Store and direct purchase), usually what I do is check if there is a price difference (usually not but some times can be). Go with the lower price. If there is no price difference, I go with the Mac App Store version, then proceed to email the developer/company with proof for a copy of the non-Mac App Store version anyway. Usually this isn't a problem.
I agree with everyone about the whole sandboxing issues and how frustrating it can be, but I definitely recommend taking a look at the App Store anyway as a user. You never know what you're missing out on.
1. I've gotten burned more than once when developers have placed major updates to their apps in the app store as separate products, requiring me to pay full price for an update to an app I already own, whereas I would have been able to purchase them for an upgrade price if I'd bought it directly from the developer.
2. I prefer the flexibility of purchasing through the developer. I use homebrew cask and love being able to install things that way. Also, developers occasionally sell cross-platform licenses if you buy from them directly.