Although participation is voluntary for VFR aircraft, shouldn't traffic radar service areas (TRSA's) be shown on vector charts?
We just spoke about this yesterday on our development meeting. This is on the short list for to be considered for 2016. As is a better way to quickly pull up a Center Frequency. Lot's of great features and enhancements coming for 2016.
Not only that, but IMHO, a VFR pilot should know he is flying in a TRSA even if he is under no obligation to make radio contact. If nothing else, he can monitor the frequency for an increased awareness of other traffic, etc.