"why make it harder than it need be?"

As Geo said, "It is the lazy way" of parenting. 
If popping Barbie heads warrants a hit, then so does an endless list of misdeeds. Did your son do it out of malice or did he want to see what's inside? Looking for Barbie's brain?

Removing his favourite toy for a few hours until he got the Barbies back together again might have been just as effective and prompted a bit of thinking on your son's part. As adults we know that if we damage other people's property we risk losing our own. 

Not a bad lesson for a youngster to learn... no need for a hit, nor a two hour lecture. Plenty of effective & instructive options in-between.