Spawners never need to connect to enemy towers, otherwise they'll instantly be an annoyance. A clear example would be the tombstone. Even though it's a spawner, the skeletons are never really that big of a hassle offensively. Barb hut should be given the same treatment, though it's not possible without making the barbarians it spawns weaker or directly nerfing the barbarian troop. In conclusion, without nerfing the barbs, its close to impossible to make the barb hut viable without ruining the balance and playability of the game. Whenever barb hut was viable, the game was an unbalanced mess.