I have never crimped any of my 223 loads,but if the brass(neck) is over sized for some reason I don't think it could hurt. I have had to crimp some 30/06 brass because the neck was a little over sized.
I use the Lee factory crimp die with ALL my .223 loads. If the bullet does not have a cannelure, I keep the crimp light to not bugger up the bullet. For basic paper punching, a crimp is not needed and may be counter productive. Some bullets do not respond well to having any degree of crimp as the jacket gets deformed and accuracy can go to hell in a handbasket. If the ammo might be used in a fight, crimp it to prevent bullet set back and putting the rifle out of commission.
If the bullet has a cannelure, you may as well crimp it.
However, this all depends on what you are loading for. If you are going to be doing varmint calls, where you're going to be in a fixed position, high power matches, or bench rest competitions, crimping would be a detriment, as it decreases accuracy.
If you're going to be rapid firing, or moving a lot, I would crimp it. If for no other reason than to prevent the bullet from wandering around in the case...
All RCBS and Hornady bottle neck dies have a roll crimp built into the dies. To not crimp you have to run a resized cartridge all the way up screw the dies body down untill it touches the neck. Once it touches the neck now you back it off 1/2 turn. If you do not do this you always crimp your rounds.
Do you need to crimp not really. If I was using a semi-auto I would crimp ust to be on the safe side. All my 223 rounds are crimped not much but just enough to count.
I crimp only those round that the bullet will pull inder recoil. Ie. the .500 S&W and acouple of others. I also load for accuracy and with bullets that have cananlure, the canalure is usually not in the proper place to crimp into. I pay absolutely no attention to the canalure when reloading.