Nothing hard nor fancy:
Now WvW ranks obviously do not show overall class knowledge but it does restrict more clueless people in participating towards giving feedback. Atleast with certain fixated minimum rank you do gain the foundation knowledge of your frequently played class (or classes).
If you wont set in any restrictions on from whom to ask feedback from then it will be the same "knife in the back stabbing" when the last time you guys made a poll and asked what to do with red borderland. The stabbing part was asking opinion from EVERYONE (that includes a massive PVE population who doesnt play WvW) and based on that made an unwanted decision that many regular WvW players were against.
Oh who am i kidding..its anet..they dont ask opinions from anyone and make their very experienced class change decisions from ranger game plays.