Why do you say that its a new kendogi and its lasted through several months of iaido and kendo.
Well for one thing beginners generally don't wear hakama in aikido, the iaido and kendo keikogi have no trousers/pants so unless you want to walk around wearing just the jacket...
The other thing is. How many times at kendo or iaido have you had someone grab your keikogi and pull you around like that. The himo just don't last that sort of punishment, they tend to get ripped off. In aikido people will be holding onto you and tugging the keikogi a lot and kendogi are just not made to absorb that sort of punishment.