Chocolate companies spend a lot of time engineering the fat blend of chocolates so it has a high solid proportion at room temperature but fully liquid at body temperature so that chocolate melts in your mouth.
If you put chocolate in the fridge it will just take longer to make this transition when you put it in your mouth, but as it warms up the effect will be the same - assuming no one is keen on gulping down chunks of hard cold chocolate - it will just stay in your mouth longer to warm up.
I guess the spatial melt profile of it will be different, for example a lump of chocolate at a higher temperature will probably melt all at once, whereas a lump of frozen chocolate will start melting at the edge first and take longer for the entire lump to become molten in your mouth, so more like sucking a sweet than the near instantaneous transition of the whole lump from solid to liquid.
Fat bloom is kind of interesting The fat in chocolate can exist in different crystalline states called polymorphs. A bit like carbon, that can exist as graphite or diamond. In chocolate the product is made from a less stable polymorph. When the chocolate is melted and then recrystallises it may form into a different polymorph (the more stable one) with a different colour (this is the change in colour you see). The effect is harmless but is considered by consumers to be un apeallling.
There are people who spend their whole lives doing this sort of stuff. Carefully engineering the formulation of chocolate so it performs in a particular way in your mouth. I can imagine they are horrified by people bunging the stuff in the freezer before eating it and ruining the mouth feel effects they are trying to generate.