I don’t think there’s any sense in which the physical basis of thoughts is meaningless, but you are entirely correct that it’s not important. I generally hesitate to mention the “computer program” analogy because people often cannot get the fact this doesn’t mean I’m saying that the brain is a computer, but the physical basis of computer programs is a quite apt analogy.
It would not make much sense to ‘study’ software by studying media. Optical media would be so different than magnetic yet the software is the same. Maybe ‘irrelevant’ is a better word.
In any case, the far end of ‘not important’ is ‘meaningless’.