Why would you say that, anon?
Twintails are beautiful. That's an additional tail to play with and twirl your fingers around. They allow for twice as many cute hair accessories like ribbons and hair ties.
They tell a different story of the waifu's personality. You might think they're childish because they have a childish haircut, but then they're extremely mature and lovely.It also allows for gap moe when she undoes her twintails and you see her beautiful long hair.
Twintails are amazing and you're wrong if you think otherwise.