why does a world chess championship skip years? the next one is 2016.

Because it no longer skips two years, and it does conform to a schedule (although with FIDE terminally corrupt, the "schedule" rarely lasts through three full cycles).

But why ws this year an exclusion then?
It was just a little bit earlier. In November 2014 instead of January 2015 for example.
p.s: Join :D http://www.chess.com/tournament/world-pointless-cc-cup
i'm sorry but the answers here still doesnt really fully explain the reason behind why the WCC sometimes skip years and sometimes not...it's so confusing? i mean in others sports, there is a fixed number of years to win a world championship for example the fifa world cup or olympics.

Well there are many changes in Championship cycle last years, there were knockout, round robin both for title and Candidates. Probably because of changes made in 2013 (round robin instead of knockout for Candidates) it was decided to make two matches in a row. If you check you will be surprised how many changes were made into championship cycle
i am so very curious but i couldnt find any answers anywhere as to why world chess championships skip years? i mean, there's no 2015 world chess championship!
and does the present explanation for this describes past championships like the kasparov era?