9V:
professional |pr??fe sh ?nl|
adjective
[attrib.] of, relating to, or connected with a profession
Clearly, as the iPad is connected with the music profession, it is professional equipment.
Now, let's look at how you're defining toy:
toy |toi|
noun
an object, esp. a gadget or machine, regarded as providing amusement for an adult
True, the iPad and its subsequent applications can also be considered toys, in addition to the guitar, piano, computer, synthesizer, etc. etc. Even the so called "professional music tablet" you described would be able to be called a toy. According to these definitions, it is possible for something to be both professional and a toy. So what?
Broaden your horizons a bit. Open your mind to new ideas. Quit living in the past. I'm not saying you have to use an iPad to be a professional, but don't belittle the professionals that do. If I created a vast sculpture out of Play-Doh, would you think less of it because Play-Doh is a child's toy? Perhaps you'd think I was unprofessional? Nonsense.