Great post! You answered my question in the last paragraph. These fees are almost entirely due to the creation, or issuance, of Runes. It would be interesting to see a chart showing the ratio of Runes being issued versus being transferred, or bought. Would exchanging a Rune create the same fee spike as an issuance?
Runes issuers would be spending $150M a day or $1B a week Sort live, I hope. Good business for miners.