What I expected to happen is enough frequent occurence of Cold Taiga biome (and its modifications), like in previous versions of MC, and at least as frequent as the simple (not snowy) taiga.

What actually happens: Cold Taiga has become rare with the new world generator. It looks like cold taigas are now dependent on neighbourhood of ice plains. As ice plains are not very frequent, the result is that there is more probable to find a simple (not snowy) taiga now than a cold (snowy) taiga. It looks like a bug in the world generator which makes biomes depend on one another too much. Thus the MC world looks less natural than before (in the real world cold taigas are much more typical than snowless ones, and the occurence of tundra (ice plains) is not a condition for the taiga to be covered with snow).

How to reproduce: just look through any MC world. The program AMIDST may be very useful in it as it can show biomes on a huge territory at once.