I had never really thought of this before but, now I would answer my question and say "yes" pro audio is an art form.
My friend records music for other artists. He helps the artist paint a full audio picture and using his studio tools to capture it in a recording. That is an art form.
As live sound engineer, I use microphones to capture the sound waves of musical instruments and voices and sculpt those signals into a soundscape inside the venue for the audience. That is an art form.
To confirm my thoughts, I found a short article called "Pro Audio As An Art Form" taken from the Pro Audio Files web site. Click link below
Upon further research, I did find that some audio professionals believe that recording and/or live sound engineering is more of a "craft" rather than an "art form". I believe that it is actually both.
As audio professionals, we have practiced our "craft" by learning how to use all our available tools to their full potential and knowing how to achieve a desired product for any given project or production. The "art form" happens when we are actually creating the recording in the studio or building the sound mix in a live production.