Their walled garden represents easily one of the top 3 threats to computing freedom,
How do you figure? Not saying you are right or wrong but I'm not seeing a credible argument backing up this assertion.
and if you're a developer they're nothing but bad news - a nasty middleman who will dictate what your app can do and take your money for the privilege of doing it.
"Nasty middleman"? As if Apple provides no value here. Apple created the f-ing platform, both hardware and software as well as the distribution system. It is WILDLY successful and popular. If you don't like how they do it, go somewhere else. Android or Blackberry or Microsoft are all options. Whether you like it or not, Apple reviewing apps does keep malware and other shitty or problematic apps out of the ecosystem. Are there downsides to this? Absolutely. Is Apple sometimes unfair? No doubt about it. But let's not pretend that there is no benefit either. Apple has created something that a huge number of people value very highly and are willing to pay for. There is nothing wrong with being a middleman as long as you are providing value and Apple clearly does to a lot of people. Maybe you don't value what they are selling (and that's totally fine) but many others do.
For developers, the app store is a microcosm of the American dream, they'll tell you that you can make it on merit, but only a tiny minority will, the rest will just tread water and only enrich Apple in the process.
Let's be frank. 99.999% of the apps on the app store are crap (see Sturgeon's law) and do not deserve any of our money. Just because you put something out there doesn't mean it is automatically valuable to anyone else. If someone is delusional enough to think that developing a crappy piece of software entitles them to anything then I have no sympathy.
For users, it's the worst of '90s computing powered by the latest technology - a store full of shitty shovelware that you have to pay for or be annoyed by ads or restricted by a "trial version."
So every developer is supposed to live the dream and somehow be part of the 1% and they all develop undiscovered gems but you admit that most of the software is actually crap not worthy of purchase. So which is it? You're contradicting yourself. If the developers develop something worth buying, people tend to buy it. If they make shovelware then they deserve to lose money. Neither is Apple's fault or responsibility. Apple just makes both possibilities available. It's up to the developer to make something people will actually give a shit about.