Analogy to World Cup isn't good, because soccer and hockey just aren't comparable in the amount and quality of teams. However, there still should be some kind of qualification for at least the two last spots. The big 6 could get their spot automatically or via IIHF ranking, doesn't really matter since the end result would be the same thing anyway.
Everyone? thinks those last teams should be Slovakia and Switzerland (and definitely would be better to have those than the current you know what teams), but I think it isn't as clear cut with some rising countries (e.g. Denmark), so qualification would be needed.
NHL cited lack of time to arrange a qualification tournament this time but that was nothing but an excuse to have those two joke(r) teams, since they could have used IIHF ranking or past Olympics/WC results to determine the 8 teams. Of course the issue with using IIHF ranking is that NHL likes to think IIHF doesn't exist.