I know it sounds pedantic but it's not 'prefer', it's that the properties as methods is fundamentally changing the way the language works and is very brittle.
In short, it doesn't matter which it is - a method or an attribute - as long as it's consistent.
What fundamental changes to the language you see when using methods instead of plain attributes? Aside from the fact that setter and getter methods in JS are bindable while attribute access is not.
You're kinda arguing against yourself as the code won't be consistent. You're changing a part of your code but not all of it and it just leads to brittle code as you're never sure what you're working with, especially in a dynamically typed language like javascript with terrible support for editor behaviour sniffing.
Every time you have an object you have to remember whether it's a normal JS object or a properties-as-methods object. Using knockout to handle your view models doesn't magically change the rest of your code. All the other code you write and libraries you use will be using properties the standard way.
Secondly, the uniform access principle (which you seem to misquoting? It's not about consistent access by type, it's about all types having identical methods of access).
It comes across as something an academic would propose because it's intellectually enticing but practically detrimental.
Think of it like changing a, it, the, we, you, our, etc. all to be o. Yeah, now you can change nouns freely, but the syntax is a signal and the difference is useful.
A method is conceptually supposed to be different to a property and so it should look different.
Javascript's bad enough for readability with everything being a function.
Whether you agree with it or not, in the end it's simply not how javascript works. Methods and properties are accessed differently.
I hated that at first, but it's really hardly a problem when it comes to actual development. And it's pretty nice for optimization to be able to mix/control what properties on a model actually need the notification changes, as opposed to other frameworks that just assume everything notifies. (Especially useful when you start dealing with object graphs with 100s of properties).
Angular was supposed to fix this, but when I got down to brass tax I had a hell of a time remembering if I was in or out of context and then having to cast my self back into context.
At least with knockout you know you are always out of context and have to use the getters/setters.
