If you go back far enough with keyboards - they were simply called 'keyboards' then, not 'arrangers' or 'workstations', they had no factory presets, music finders or playlists. So owners would learn what their keyboards did, they'd check out all the voices and effects, and audition the styles. No user memories, so they'd write the settings down. They'd find their favourites, and realise that some combinations of voices and style would, with a little tweak here and there, work for many songs.
Keyboards became more complex, many more voices, styles and features. The market asked for (and got) factory presets that matched suggested sounds to a given style - the beginnings of OTS. Then the market asked for more and we got things like Music Finder and eventually Playlists. All good stuff, but it had the unfortunate effect that many players would only use these, and never explore the keyboard's potential. Some might only play the tunes that were in the playlists etc, and then only if they had the music.
I've always held the view, and I have since I helped design some of the first keyboards on the market, that they offered the player the ability to
arrange their music. It didn't matter if the style they chose wasn't like the original, or if the sounds they used weren't the ones suggested in the books (which were often rubbish suggestions anyway!). Isn't that one reason why we call them 'arranger keyboards' these days.
Don't get me wrong, I'm not knocking the people who only use OTS etc or those that insist on a style that's ultra-close to the original song. I'm delighted they're making music, which is the bottom line. But I'm sometimes a bit saddened to think that they're missing so much of what people like me and my many colleagues put into the instrument.
So my advice, as always, is 'arrange the tunes your way, re-style them and explore what your keyboard can do for you'. It should all be part of the fun and enjoyment of playing. If you're enjoying yourself, who cares if the style is 'wrong' or you're using the 'wrong' sounds? Go fort it!!