Packages currently handle installation of vim syntax support files inconsistently. Some builds install the files if the "vim-syntax" USE flag is enabled, while others install them unconditionally.
Do these files fall into the "small text files" category for unconditional installation? If so, we should probably phase out the vim-syntax USE flag. If we want to keep the USE flag, I would suggest documenting a global policy regarding its use. Should that live in the devmanual? Or maybe the Vim project page?