I, too, am one of those that believe in cool temps rather than hot (my car ac is set to 18 degrees, and I sleep with windows open even when it is subzero outside)
As wassaid above, if you are cold you can always add a layer to be warmer, but if you are too hot there is nothing you can do.
My belief is that the cabin crew set the zonal temperatures based on their own comfort levels - bear in mind they are normally seated next to the doors, which will be cooler than elsewhere.