Hi Nikita,
The experience you described is referred to in the Goenka’s tradition as bhanga (dissolution), NOT the bhavanga (dormant state of the mind) as explained in abhidhamma.
I never experienced bhanga when I used to practice in this way, but I read extensively about the “stations” in the Goenka’s technique. You’re right that it’s not something to crave for, but it is also recognized as an important “station”, because it means that the mind is sharp enough to experience such subtle vibration.
Recall that this technique takes bodily sensations (representing vedana) as the main object of observation. It starts with the breath just to sharpen the mind for this task, and as the mind is sharp enough it can perceive sensations arising and passing rapidly.
Also, “anicca” in this tradition means the arising and passing of sensations, and so bhanga is an important stage because the mind is perceiving this arising/passing at a very subtle level.
I know nothing by experience about kasina, jhana. I just want to point out the bhanga/bhavanga distinction.
Best,
Lang