Helmets were brought in with safety issues in mind (awkward falls, errant sticks and pucks, etc) in order to prevent injuries. However, they still did detract from the game in terms of fans being able to identify the players as shown in the photo.
You would have to go back to the 1930s or 40s to when NFL players did not wear helmets, but it is interesting to note that many NHL players continued to play helmetless well into the modern TV era (1960s to ‘80s era) and that helped, IMHO, the NHL become popular as a result.
The collective bargaining agreement allowed players who were playing in the NHL at the time had the option of not wearing a helmet. Players not already in the league were required to wear helmets.