The only reason I bring this up is for the new Jungle/Rainforest's. I hope we dont change maps, This change isnt that big enough for a new map. (At least i dont think)
We don't change for new biomes. We change when there's massive terrain generation changes that create 50 block high cliffs that change biomes randomly.
As neat as those look... I'm highly, highly doubting we will update for 1.2.0. That is at least terrain people can hand-create, since it isn't adding any new colored grass, mushroom blocks, mobs, etc.
we could always change map expansion if this current map size is too small.. ex enlarging from 12 x 12 to 24 x 24
o_o 24k x 24k?!? That's absolutely HUGE.... Our world is huge already, four times it's size is just overboard..... I doubt that will happen, lol. Although, you made a point, enlarging the map could do it, but it's already huge as-is.