It's worth remembering not only that the various Nobels are awarded by different bodies, but also that Nobel himself set down specific criteria. All winners are chosen from lists of nominees, and the literature prize is for the nominee who "shall have produced in the field of literature the most outstanding work of an idealistic tendency"; that is, it is a judgement of quality and purpose. and not of how well-known, popular, or indeed financially successful an author has been. So awards to authors who are little known, or well known in a single linguistic community, are quite in order (as with the Booker for British and Commonwealth novels in English).
And an injunction to "stick with the classics" is somewhat ironic in this context, in that it's a statement that one should always defer to the cumulative weight of transhistorical popular opinion. But how many "classics" and their authors have gone unknown or unrecognized in their lifetimes? Were they less good then simply because nobody had yet considered them fashionable? If everyone were to "stick with the classics", no new work could ever become a classic!