In 71 BC Crassus crucified 6,000 slaves on both sides of the road from
Rome to Capua; the Appian Way. They were the remnants of Spartacus' army.
Now, that you can call "brutal"; but it is understandable. Rome was a
slave-society; it depended on slaves very heavily. And Spartacus had
been marching up and down Italy with his army for months, pulling in
more and more runaways and defeating full consular armies. Crassus had
to lead in 7 legions, and Pompey came back from the east with his
legions too.
Something spectacular as punishment was called for as a deterrent.
Brutal? Yes, very by our standards, but that was the way Rome kept its
hegemony.
OTH, to just crucify some dogs every year as not much more than homage
to an event in ancient history is stupid; yobbish and mindless.
Ed