I think homebrew and MacPorts are niche though. Your "normal" OSX user wouldn't install them. Heck, I ran Linux for years and years and I haven't even installed them under OSX because if I wanted to run BSD or Linux, I'd have installed BSD or Linux.
It's like installing all those GNU tools on Windows to make it more like Linux, and putting Homebrew etc. on OSX to make it more like Linux. Why not just use Linux or BSD? I never understand it.
Also, the lack of proper Quartz windowing support from X11 apps makes using them painful.
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
I'm a developer (I develop on OSX and Windows every day for my day job and at home for myself) and I do not use homebrew. There is not anything I am really missing, but I write C++/Obj-C and you might write something different.
It is interesting regarding the state of app design as most of the BSD or Linux software looks odd to me!
I agree that Windows has some odd looking software but they do typically offer more features - you don't get MDI under OSX.
It's like installing all those GNU tools on Windows to make it more like Linux, and putting Homebrew etc. on OSX to make it more like Linux. Why not just use Linux or BSD? I never understand it.
Also, the lack of proper Quartz windowing support from X11 apps makes using them painful.