If it hadn't been a walled garden, the market would have sucked horribly inside of a year. It would be a steaming cesspool of malware and trickery and junkware. Consumer trust would have been eroded, and the market would have failed.

I think that Apple did absolutely the right thing for a young marketplace. It was bad enough as it was (remember the $1000 app that did nothing? And the game with a $100 in-game purchase of ammo?)

The Mac wasn't a steaming cesspool despite having none of these restrictions. I don't think your examples at the end support your point at all. It seems to me that a $1,000 app that does nothing and $100 in-game ammo purchases are only enabled by something like the App Store. The App Store is pretty anti-consumer, really. For example, the freemium craze was partly driven by the fact that Apple forbids free trials, so developers had to come up with other, worse ways to monetize without requiring people to pay up-front for something they didn't know the worth of.

The iOS marketshare is a orders of magnitude larger than that of macOS so the target vector is larger. Malware and the like would be hugely more profitable on iOS than macOS.

I have no doubts that if Apple had been more open in terms of publishing apps for iOS, the App Store would closely resemble the current Play Store in terms of malware and junkware. Something as personal and often-used as a smartphone is just too tempting of a target.

It is now, but it wasn't when the App Store was introduced.

In any case, malware is best prevented by strong sandboxing. Forcing everyone to go through the store does approximately nothing to fight malware.

Sandboxing has proven pretty weak in mobile products (definitely in the case of Android; the iOS sandboxing has had a better track record).

Additionally, not all malware needs to escape a sandbox. For instance, there are a bunch of fake apps that simply capture credentials, or that make expensive phone calls or texts.

A well-run store that can run tools against images is a decent first line of defense against malware. A store also provides reliable information about code publishers. These are not a complete defense, but they appear necessary.

A big part of Android's problem is that the permissions model sucks. Until recently, all permissions requested by an app had to be granted up-front as part of installing the app. Apps tended to request anything and everything for no good reason. This trained users to just click through the permissions screen without paying any attention to it.

The iOS model (and now Android model) of prompting for permission when the app first tries to use it is much more solid. If an app requests access to your contacts for no good reason, you'll get a fairly obvious prompt and you can say no. There's still some trouble with getting users to pay attention, but it's a lot better.

I don't see how this makes a store appear necessary. Android doesn't allow sideloading by default, and iOS can now sort of sideload apps using the new free signing stuff Apple put out. The limits on the number and duration of sideloaded apps make them impractical for selling legitimate software, but are no obstacle to malware.

Could you elaborate on what makes you sad about their approach?

We might have been able to have mobile devices that look and act like PCs, with full user control, high customizability, etc. Instead, we get locked-down devices. Android is better, but Google seems to be gradually following Apple's lead on this, and it's sad enough to me that Apple's mobile platform isn't open and customizable the way their desktop platform is.

What's even sadder is that the success of the iPhone has encouraged people to try to lock down what were once more open platforms.

I totally agree. Apple's success with the restrictive model seems to be creating a lot of imitations, which is really terrible. We can handle one or a few platforms being this way, but if they all end up like that....