All software has to hardcode something at some point, this is unavoidable. I don't use GNOME either, but they do make it very easy for newcomers to contribute and to change anything they want. It's open source after all, the control is in the hands of the user.
I don't follow. In my experience setting up a build environment and changing a couple lines of code provides a lot more control (and is a lot easier) than rewriting the whole thing from scratch or ditching it entirely for something else. If your distro's package manager supports source builds then you probably don't even need to use tools like GNOME Builder to make quick modifications.
If you find setting up a build environment to change a few lines of code more reasonable than switching to software that wasn't so boneheaded as to hardcode the value in the first place, then good for you I guess. I personally don't have much patience for it.
There is no need to set up a build environment. GNOME Builder does it for you, for GNOME packages. For other packages, on my distro (Debian) the package manager does it for you. It's 4-5 commands to download dependencies, download source, rebuild and reinstall ANY package. Comparatively, the cost of switching can vary wildly depending on the software and available alternatives.
