I don't have it installed on my Macs - what am I missing? I write C++ daily on them.
EDIT: Seriously, what am I missing that I'd need as a developer? My dayjob is on a Mac Pro writing desktop software and my hobby at night is on a MacBook Pro doing the same; it's on neither machine.
brew is a package manager, I can install a set of applications and libraries that will be kept up to date with a simple command line. If your coding doesn't take you outside of what Apple provide then you are probably not missing anything.
Personally I have the Android SDK and NDK, QtCreator, Qt5, cppcheck, cloc, mongodb, node, wine and others. If you are not using a variety of 3rd party tools to produce/automate your work then you probably don't need to worry.
Having all those kept up to date for me saves me so much time.
I use xcode and use wxWidgets, but I grab these manually and compile them myself. I also use the Android SDK and NDK, cppcheck cloc etc like you
I didn't realise that they could be kept up to date with homebrew?? Is that the case?
Last time I looked at MacPorts (and perhaps homebrew) I saw it as a porting of BDS/GNU tools to OSX and therefore making the OS more Linuxy to my mind. I wanted a clean break from Linuxland when I moved to OSX, hence I removed MacPorts etc. (Additionally the ported software all ran under X and not Quartz so it didn't really fit in; also, the fetched packages and compiled systems were massive in size which I didn't appreciate on a laptop that shared space with recorded audio and video etc. so space was at a premium).
Homebrew is really the default package manager. You don't need it, per se, but for the vast majority of people it'd be like trying to set up a Linux system without using apt-get or yum: an exercise in pain.
job: here is your macbook pro, welcome! you: <install homebrew>