A comprehensive list of typographic conventions in comic books, including the Crossbar I rule:
An “I” with the crossbars on top and bottom is virtually only used for the personal pronoun, “I.” The only other allowable use of the “crossbar I” is in abbreviations. Any other instance of the letter should just be the vertical stroke version.
Until reading this I thought my own preference for the Crossbar I in these cases was some weird personality defect. Now I can fire my therapist and add OpenType ligatures for the Crossbar I to all my fonts instead.