Hello Frieder,
Sorry to hear that. But well, the decision is up to you.
Regarding the use cases, I believe they’re the same as on Desktop. For example, recording a demo/sketch of the track to programmed drums - no longer possible in case there’s a tempo change within the track (imagine you’re making a cover of, say, Franz Ferdinand “Take Me Out”, or Daughter Darling “Things Untold”).
Even worse when composing with iPad - one is basically not allowed to compose any music with variable tempo.
Maybe for dance floor oriented music this isn’t a frequent issue, and the intended targeting is for that kind of music, thus it doesn’t seem like a big issue to you. But I believe even in dance music tempo changes are used sometimes for effects (like track build-up by accelerating tempo at the beginning, slowdown at the end etc). And that kind of targeting seems just too narrow for no particular reason IMO.
Hope this explains it. Regards.