To add to the thread, I'd like to correct you on what they meant by "counter." They don't mean it in the sense as countering against something else, but in the sense of actually counting the number of something. Japanese has that for a lot of things, such "nin" for people, "hiki" for for animals, and in the case of the thread, "hashira" for gods/buddhas. And on that note, yes, Kishimoto did think when he named them. Itama is the plank of the floor, Tobirama is the door to the temple, Hashirama is the pillars in the temple, and their father Butsuma is the Buddha in the temple (butsu meaning buddha, and the word butsuma actually meaning the part of the room in a Japanese house that has the shrine to a dead relative, where they often ring the bell and place incense, fruit, etc.) The Senju represent buddhist, "temple/house" ninja.
An interesting note is the Uchiha family (Madara, his immediate family, and the leader of Uchiha in general.) The Uchiha, as usually discussed, represent a Shinto/ distinctly Japanese aspect, from their eye techniques, to even their names. Izuna is the name of a mountain, in addition to where a similarly named tengu/cult to said tengu originated from. Madara is actually the name of a demon-god mask used in Shinto ceremonies (which may have been part of Obito's use of a mask throughout the story.) Tajima is the name of an old province in Japan, in addition to a place where major Shinto shrines are located, and a "holy pathway". Lastly, Fugaku is another name for Fuji, which is the most holy shinto mountain.
Kishimoto usually names dynamic characters a certain way for a reason.
