I respectfully disagree. For many of us, it's not all about the sound; no, it's more about the
music. And the music points to the means of triggering the sound, which, in this case, is a keyboard. The feel that the player gets from the keyboard can influence the music every bit as much as the sound can. Have you never played a really cheap key bed and said, "Yuck, I don't even want to touch it"?
Miniature keyboards are nothing new. The Baroque clavichord has a miniature keyboard, but it's one of the few instruments that does. It's not for meaningless arbitrary reasons that the key size that is most common today has become the most widely accepted. It's due to the fact that it's the most comfortable fit for the average sized hands and fingers. A miniature or slim key size might suit yourself or a child, but it most certainly wouldn't suit someone with a big fat fist and fingers like egg rolls. And as we get older, our hands tend to get larger...as does everything else.
My wife has a Korg Minilogue XD, which has the miniature keys. I've played it quit a bit and like the instrument, except for the key size. I find certain things like trills to be nearly impossibly to play on it well. Even more, playing on it for extended periods of time, and then switching to a full size key, invariably results in mistakes until my mind and fingers have adjusted to the different key size. This is especially true for held intervals. Try playing a tenth interval with one hand on one keyboard size, and then suddenly switch to the other size. Play a series of parallel tenths up or down the scale, and tell me that switching key sizes midway doesn't result in mistakes. To each their own, but I try to avoid mistakes. Why risk one, ever? Playing well is already difficult enough without the problem of key and interval distances changing right in the middle of a piece of music.
I would never buy a miniature keyboard for these and many other reasons.