I have found LabVIEW to be a truly useful software application for over a dozen years and have never felt limited with 16 symbols, 5 line styles, 6 line widths, and 256 different colors.
In any case, you probably want to make feature requests directly to NI at their
product feedback page. It's been my experience with the NI that they listen closely to what the users what to see in future releases. Another good way to make your wishes known is to attend NI Week in Austin where you have the ability to talk directly with the LabVIEW development team.