Its simple: it just plain works. Pretty much, always. I plug in a MIDI keyboard and Controller, fire up a synth app, and off we go. Stable, sounds great (comparable by far with any PC plugin), and just plain works. I have two iPads and an iPhone in my studio rig now, plus a couple of Akai controllers (pads/keys/sliders/knobs), and as a portable action studio this configuration just rocks.

Plus, I don't have to have it sitting there, like I'm checking my email on stage. Hate that about laptop musicians, as if it is actually interesting to watch someone glow their face when I'm out at night and want to have fun, away from the office .. with the iPad form factor, at least, it lays flat and stays out of the way. And there is no QWERTY keyboard, so its not easy for someone to make the association "that guy must be writing an email onstage instead of making live music", and believe me that happens a lot with laptop musicians around my parts.

Because...magic. And fairy dust. And nobody who uses a laptop could possibly be cool.

It's not a great device for making music. It's an adequate device mostly used by hipsters (and I use that term offensively) to look cool, sort of like how "writers" hang out in coffee shops using Macbook Pros (or various other expensive laptops, like Vaios) to "write" the next American Novel.