Random Riddle: Drift With The Current

I drift forever with the current
Down these long canals they’ve made
Tame, yet wild, I run elusive
Multitasking to your aid.
Before I came, the world was darker
Colder, sometimes, rougher, true
But though I might make living easy,
I’m good at killing people too.
 
Random Riddle: Drift With The Current