The thing about an onboard sampler is, nowadays, few actually USE the sampler as a 'sampler'. Few record the sounds using the sampler any more. It's so much easier and more convenient to use a digital recorder, DAW, field recorder, whatever, and then fly the samples into the keyboard AFTER you have done your layout and even maybe some basic programming and looping them in a nice, big-screened computer.

All a sampler on an arranger really needs to do, for probably about 99% of us here, is load in sounds the arranger doesn't already have. This is where the flexibility of access to different multisample formats is critically important. Yamaha's loses a LOT of it's usefulness by arbitrarily restricting its multisample import to its own proprietary (and somewhat underwhelmingly supported) format, ignoring Akai, Soundfont, and GIGA formats.

Korg improve a bit by adding Akai, though. With sampler RAM being at a premium, those older Akai libraries are our best bet for fitting as many good sounds in as we can (they used to have a 32MB limit on RAM in older Akai's, so sound design was RAM efficient, usually), and this format should be on as a minimum, IMO.

But we have gone beyond the old school sampling in the sampler itself for most practical purposes.