Since product development is all about priorities, one useful exercise when you’re suggesting adding something to a product, is imagining what could be removed, that would have similar scope.
So if you were the product designer of the Syntakt, what feature of similar size would you remove in order to gain the sample engine? Or what would you trade song mode for?
Sometimes that exercise helps you realize that it’s really hard to fit everything in one box, and still have the same target audience. In this case, it seems they are focusing on three things: drums, synths and jam performances. It’s really hard to take one feature from those three focuses in order to add something that would add benefit in another area.