Just to clarify, I think you're mixing up types of crimp. There are two types of crimp, a roll crimp and a taper crimp. Revolvers (as you mentioned above) use a roll crimp to roll the brass into the cannelure of the bullet. This is essential for revolver caliber cartridges.
A taper crimp is not the same - and may be used on any semiautomatic pistol caliber, should the reloader choose to use it. Generally, when a flat bottom bullet is inserted into a straight-walled case, the reloader must flair the mouth of the casing. This is called expansion. When the bullet seating die is used, it pushes the sides of the brass back into the correct dimensions, holding the bullet in and creating more side tension.
But... there are some calibers - 45ACP being one of the most necessary - that use a taper crimp to ensure proper feeding in a tight chamber. 45ACP, 40 S&W and even 9mm all get taper crimps in my opinion, so it ensures that they'll feed in anything. Without a taper crimp, the bullet seating die may not return the brass back to its original size after expansion, and chambering can become an issue. Also, without a taper crimp, cartridges are more prone to shortening after repeated chamberings. It's not that the case was sized improperly, its that force on the bullet during insertion into the chamber can cause it to shorten - even on the first chambering.
Remember, taper crimp and roll crimp are not the same thing. One is for use on bullets with cannelures, and one is for use on bullets without. Over crimping can cause accuracy problems - but non crimping / under crimping can cause feeding issues in picky firearms.
thanks! good information! Rep'd.