Not wrong, not right… Depends on what you want.
The handicap is designed to keep the game of two different ranks fun for both sides. (maybe with a stronger emphasis on the stronger player). The stronger player is not bored, because he has to compensate for the handicap and try hard to catch up… The weaker player, on the other hand, stays motivated throughout the game, because ha actually has a chance to win.
I on the other hand, do not like to play handicapped games that much, because in my opinion it hinders the learning process. To close the initial gap the stronger player usually has to “overplay” a little playing moves that would not work against an equally ranked opponent and the overall style is also different from equal matches. Thus the weaker player can learn bad habits and stronger player reinforces them. If you play without the handicap it is much easier to play simple, solid moves that the weaker player can mimic to improve his game (but granted, not so much fun).
It is my believe also that handicapes are far from being “precise”. Even a very strong player for example can lose easily in a handicapped match if he has no experience with it, because the style of play is so different. Thus it is no reliable way of comparing ranks. Thus it should unranked. (In my opinion)