I will give you another reason to anneal cases, reforming to another round. I used to shoot 6.5mm TC/U and 7mm TC/U a lot, if I just used the .223 parent case and ran it through the resizer I could bet on split necks, maybe 8 or 9 out of 100, I know that doesn't sound too bad, but when your going to make 500 to 600 cases it adds up. By annealing the necks before I reformed the brass I would loose maybe 1 or 2 per hundred.
So there are quite a few reasons why to do it, I know BPCR shooters that shoot in national level events that do it ever time they reload a case because they want the brass the same every time, that is a little too much for me, but then I never resize my BPCR brass, just deprime and reload it.
Greg