Happy New Year!

I was wondering why the Polish for 'Happy New Year!', which is 'Szczęśliwego Nowego Roku!', is in the genitive. Is it like the French partitive genitive?
To start with, the genitive form complements the verb 'życzyć', i.e. 'to wish'. Thus 'Szczęśliwego Nowego Roku' is short for 'Życzę szczęśliwego Nowego Roku!' But then again, why is the object in the genitive and not, say, in the accusative? The answer to this is that when you use the verb 'życzyć' you put the object in the genitive to wish someone luck or even bad luck (as in the jocular '(Życzę) połamania nóg!' = 'Break a leg!'). Since luck is uncountable, this brings us back to the original idea of the partitive genitive. I suppose the genitive is there to express the fact that here we (Polish speakers) treat a year not as a complete whole but as an almost open-ended period since it is unfolding, so to speak, it has yet to begin properly. When in Polish we ask someone about the past, we use the accusative, so that 'Did you have a good year?' has a direct equivalent: 'Miałeś (masc. sing.) dobry rok?', showing that the year that has finished or is about to finish is a closed chapter. My conclusions may be a bit far-fetched but I think there is something in the nature of a new year - its unpredictability in particular - that makes us wish someone '(of) a good year'.
The same holds true for 'Wesołych Świąt' ('Happy Holidays', esp. for Christmas and Easter) and 'Wszystkiego najlepszego z okazji...' ('All the best for...'), which is why I may be wrong. Or perhaps these are shorter periods of time which too are shrouded in mystery like all the future.

Happy 2013 to you all!