I agree about FreeCAD, lacks a lot of polish, but there's a big update coming from it seems basically one maintainer that looks pretty promising. I found it looking for a way to save in a git-sane format (which this branch/fork has). Main problem with Fusion360 (for me) is the lack of Linux support.

My assumption is that it and other standard CAD packages would have a greater learning curve for a programmer who mostly wants to print simple but custom objects. Granted, I have a background in non-CAD 3D, but OpenSCAD was incredibly fast for me to pick up not just because it relies purely on code but that it eliminates a lot of concepts that you are forced to learn otherwise.

In OpenSCAD, there are no units (though STLs seem to come out in millimeters), no object hierarchies, no sketches, no key combos, etc. All you have is code, in a domain-specific language, that describes what is being built. This can be difficult or unappealing, especially for someone who isn't a full-time programmer, but it can also be freeing to just deal with code and not have other things potentially get in the way or cause confusion.

Of course OpenSCAD probably doesn't scale the more complicated a project gets. But for Arduino/RPi boxes, replicating parts, screws and bolts (given a 3rd party module), it's a powerful and handy tool. However, it might be horrible for someone with limited coding skills.