Later models (starting in the 90s) have "CD quality sample" and probably aren't particularly worth sampling.
However some late machines such as the MPC series have audibly special sequencers, and "swing" in their own, peculiar way. So sampling individual sounds isn't particularly interesting, but sampling drum loops can be interesting.
Best explained by Roger Linn himself:
> My implementation of swing has always been very simple: I merely delay the second 16th note within each 8th note. In other words, I delay all the even-numbered 16th notes within the beat (2, 4, 6, 8, etc.)
https://www.attackmagazine.com/features/interview/roger-linn...
Convenience and also price. A real Roland TR-808 will set you back about $5,000 dollars on the used market.
I suppose, then, these would be analog drum machines and the sampling is for convenient use in a digital workflow?