Coin Obverses

The obverse of the Spanish Coin is the side with the king's portrait, name, and the date. In almost all cases, the reverse is used as the vignette. An exception is the New Bedford, MA (?) scrip note. Why so few obverses? Here are some speculations:

Americans had a dislike for royalty stemming from our British colonial experience. Note designers would not choose to put a king's face or name on an American note.
The obverse had the date, usually much earlier than many of the notes' issue or due date. Designers may have been concerned that those whom they hoped would accept a note would consider the coin's earlier date to be a sign of the note's obsolescence, and hence questionable value.
The obverses of the coins changed when there was a new king. The reverses stayed invariant except for mintmark.
The coin's denomination is on the reverse.