It is said that the stances in Shotokan got lower as Yoshitaka Funakoshi (pictured in a kokutsu dachi here) started to put his own touch on Shotokan Kata. Gichin Funakoshi (also pictured here) was said to use a higher, shorter stance.
Either way, we often train in lower stances for a couple of reasons: it strengthens our lower bodies and it drives home the principle of solid contact with the ground. It’s no secret that a flimsy stance makes for crappy karate, but a rooted, solid stance is a Shotokan hallmark.
I have the pleasure of training with several Karate-ka who are 5th Dan and above, and it becomes immediately clear that when they assume a good Shotokan stance they are essentially immovable, and yet, through years of conditioning the lower body and the body core, can shift and step with impressive speed.
I liken this to a palm tree that stands strong in gale-force winds. The reason it remains upright? It’s very well rooted.