Also, the wealthy trait decreases unrest, unless its being displayed improperly. Since I usually only get that with my settled governors (or after a few generations of family) the personal security is not really a problem for me. And bovi's responses seem to jive with the in-game descriptions of the traits. If you look through the history books how many times does a great victor get pre-emptively killed by a jealous rival or paranoid king? I, for one, can perfectly understand the rationale.
As for (1) I would expect that is to make the Belgae provinces very hard to conquer by the AI, as it should be. More than once I have witnessed the Sweboz spending a couple decades trying to subdue the Belgae provinces.