I personally have nothing against multiboxing as long as you're not allowed to PvP while multiboxing.
And why? Because if you break multiboxing or dual boxing at least (2 rather than 3-5 characters)down you get this: twice the costs, half the money, less xp (not half but I don't remember the formula), twice the amount of drops needed for certain quests - some which have a horrendous droprate.
Sure you might be able to solo certain group quests or elite mobs - but to me, the price for doing so offsets the perks for doing so, besides some classes can do so anyway. Multiboxing dungeons? Sure, but unless you're rolling five paladins or five warlocks you'll be needing to cough up about 450g for mounts at level 40. Besides, multiboxing is and was allowed in retail.
I'd rather see that they put an effort in weeding out and banning bots, as those are the type of "people" who ruin the game. Yes, I've dual-boxed in the past and it is not an experience that I'd call pleasant by any stretch of the imagination, sure alot less downtime which is nice when you're playing a class that otherwise might suffer from it (warriors, priests, mages...), but I personally have no intention on dual or multi-boxing on Kronos or any other server as I found the experience a drag to say the least.