I think the key point here is this: you're right that regular users don't need homebrew; developers certainly do. By having an analog of homebrew for Windows, Microsoft can attract more developers, which then would translate into a better app infrastructure for Windows. This would then clearly benefit regular users as well.

I haven't used Windows in a very long time, but whenever I sit by a friend's computer, I find it astonishing how badly designed Windows apps are. Certainly Apple's fixation with design created a culture of beautiful apps. But having more developers would also probably improve the situation