I don't often need to edit the files (I also mostly use for searching and my most common editing action would be pretty printing which I could well manage externally if need be). However, I very commonly accidentally edit the files due to a stray keypress, so if edits are not disabled entirely then not locking up or crashing if edits do occur would definitely be a requirement. Occasionally it useful to be able to edit, and it's nice to have at least an editor that can do this.