It's common knowledge that a female Force-user's power can be measured by way of their breast size. Where do you think that extra Force energy is stored? Judging by those H-cups on Ahsoka, I'm guessing she's going to have a very long run as empress.
Yeah, but I don't see a reason why would they do it. It's like their sixth sense, they can store memories in it and long lekku is sexy for their kind... anyway.. you can still say she lost part of it in epic duel with someone