True, Rome was at peace with Armenia but, while this peace was being celebrated, a revolt was beginning in Judea that would last past Nero's death, through the Civil Wars of 68-69 AD and into the reign of Vespasian. Peace was tarnished long before our coins lost their mint luster. This type was issued in gold and silver as well as each of the bronze denominations. All coins of Nero are popular with collectors since he is one of the few names of Roman rulers known to people with no interest in Roman history. Nero's coinage in general is particularly rich in interesting types and the artwork of the period was frequently quite excellent.
Demand causes a market even for embarrassingly bad, rough examples like the left coin.
At least the coin was struck well enough centered that the important legend survived. Much of this coin's problem is the result of harsh cleaning that removed the natural patina leaving a rough, raw copper surface. By comparison, the right coin retains this patina which hides the color of the copper. Both coins started out with the same red copper color. Most collectors prefer coins with this natural patina left intact.