I fail to see how these scenarios are even remotely analogous. Closed systems are what the consumer has happily chosen for their phones, which they vote for with their dollars. Our system of government is what people have chosen -- and you will note that it is not "open". I can't walk up to the Senate floor and present a bill, nor can you. The system for doing that is closed. If you want to be a part of if, you have to be vetted by the people.
I have yet to have a customer bring me an Android or an iOS device that was ridden with browser toolbars, malware popups, or link re-directors. I probably get 4 or 5 customers a week with this problem in Windows 7, 8, or 10. Any random business or small town cop shop I walk into is guaranteed to have at least half of their computers infected with something or other. People practicing law who are totally oblivious that their search has been hijacked by Conduit or one of its clones. This is because Microsoft is much more open than iOS or typical Android installs. Everything most consumers get on smartphones comes from vetted stores owned by the OS developer. While there have been a few things that have snuck under the radar with both Google and Apple, for the most part if you submitted Conduit to the App Store, I'm pretty sure someone from Apple would drive to your place and punch you right in the face. And this is why people prefer the closed ecosystem. They want to get work done in their field and not hassle with doing work in another field they don't care about, like IT.
Windows gets full of malware because "download executables from the internet and run them" is the expected way to install Windows software, so the process for installing Conduit is no different than the process for installing 7zip or Adblock.
What you're making the argument for is a package manager with vetted packages, not a prohibition on advanced users installing anything outside of the package manager using a different method.
I have yet to have a customer bring me an Android or an iOS device that was ridden with browser toolbars, malware popups, or link re-directors. I probably get 4 or 5 customers a week with this problem in Windows 7, 8, or 10. Any random business or small town cop shop I walk into is guaranteed to have at least half of their computers infected with something or other. People practicing law who are totally oblivious that their search has been hijacked by Conduit or one of its clones. This is because Microsoft is much more open than iOS or typical Android installs. Everything most consumers get on smartphones comes from vetted stores owned by the OS developer. While there have been a few things that have snuck under the radar with both Google and Apple, for the most part if you submitted Conduit to the App Store, I'm pretty sure someone from Apple would drive to your place and punch you right in the face. And this is why people prefer the closed ecosystem. They want to get work done in their field and not hassle with doing work in another field they don't care about, like IT.