In my humble opinion it seems reading and writing on the Bible is showing reverence to God because you are actively engaged in studying His word. The Bible is not a religious artifact, it was written for the express purpose to be read and studied. It is paper which can be reproduced over and over. If it helps a person to study by writing in the book itself then it probably pleases God that one is engaged enough in His word to use visual aids to study. Reverence should be for God Himself, it is His Spirit and His nature that we revere not a printed paper book.
Even though the Word of God has power; it is not the actual pages that have the power it is the Spiritual God Himself and in us that has the power. The power is from the spoken word rather than the written pages. The Bible is a tool to understanding God. If writing in it helps to understand God Himself than why would it not be appropriate? What is appropriate is that we are engaged and have enough zeal to continue in our quest for understanding Gods word. It is the actual word and not the pages that should concern us. This is my opinion only.
God Bless us everyone. :tiphat: