Generally speaking with those sorts of small indie programs you are paying for quality and convenience. Having to do "a little bit of hacking" and - especially - running an X server on macOS as your primary window system so that you can have some customizability doesn't exactly bring quality to my mind, but it might be me :-P
(of course for some the ability to be able to edit the source code of their window manager might be something they absolutely need, but they may just not be the target audience and... well, even then, you don't need the license to be open source, just the source code available and perhaps a license that allows sharing patches among people who already have the code)
> Generally speaking with those sorts of small indie programs you are paying for quality and convenience.
If I care about convenience, why wouldn't I just use the default WM?
Quality is also debatable. For a WM productivity is far more important than quality.
> If I care about convenience, why wouldn't I just use the default WM?
Because it might not have the functionality you want. Things aren't black and white, but one solution might be closer to what you need than jury rigging something yourself.
> Quality is also debatable. For a WM productivity is far more important than quality.
We'd need to agree both on "quality" and "productivity" here since those do not have well defined meaning. For me when it comes to software that helps me be productive, quality includes it helps me be productive, so there isn't a relationship where i can say that one is more important than the other since one implies the other.
(of course for some the ability to be able to edit the source code of their window manager might be something they absolutely need, but they may just not be the target audience and... well, even then, you don't need the license to be open source, just the source code available and perhaps a license that allows sharing patches among people who already have the code)