Blanching carrots before freezing helps to actually retain many great qualities - including colour, texture and even nutritional value. However, you can most certainly freeze them without blanching them. You'll need to use them up faster (within 2 months). And do bear in mind that even if you don't blanch them first, they won't be the same as they were before you froze them. They won't be great for munching on raw so aim to use them for purposes when they will go on to be cooked 'in' something such as a soup or a stew.
If you want to serve your carrots as a side dish after freezing (such as good old roasted, boiled or pan-fried carrots) then blanching is the way to go, as it will help retain the vibrant colour.