Ye gods, where do I even begin with this...
Vector layers was a 2006 Google Summer of Code project. It was too ambitious, it wasn't completed, whatever good bits were done got merged years later so that the code wouldn't be lost completely, and there is still no user interface for any of that.
But the sole reason this project was assigned was because people behind GIMP were quite open to having better drawing tools in the program. They just lacked the time and the motivation to work on that.
When your program is primarily intended for image manipulation and you have a crapton of requests from users to add image manipulation tools, filters, and whatnot, how else do you prioritize your work? Especially when you program's architecture turns out to be inadequate for complex features and you have to rearchitect and repurpose 800K LOC, not to mention updating it for the next generation of the UI toolkit that is a moving target of its own?
For every user complaining about not having shape tools you'll get three complaining about the UI, another two or three complaining about not having non-destructive editing, another two demanding layer styles, then an assorted group of individuals wanting CMYK image mode, LAB image mode, more use of GPU, AI features, more filters, better HiDPI support, and the list goes on. All the while you have essentially one person doing 50% of all work and a small team of people all working on small items. All the while there are free/libre applications like Inkscape that have been providing better drawing tools for years.
So I'll ask again: given all that, how else do you prioritize your work?