Problem is, that games are expecting to be "fun". Though subjective, it applies to board games and others too. Try applying the same "cheating is fine" arguments to poker and dice games or even chess and you should notice how wrong certain arguments are. If games are not fun, people are not playing them. If people are not playing, the cheaters loose victims (loss), the company looses income (loss) and the normal players loose people they might have needed to experience other parts of the game too.
For minor offences you would have a point with the "feature", but i would not call combojumping effects minor. And if funcom even takes it as a feature and applies it to their internal "balance" calculations (if they have them), it makes matters even worse and results in crazy nerfs and tweaks (some of we have even seen already) to classes. All the time leaving the honest players (the majority!) behind and frustrated.
Also they would have to include it in the tutorial and explain how to do it. But then they should change the name of the game, too. Because it will be Age of Bunnies and not Age of Conan.