It only requires interrupts for melee heavy groups. Ranged heavy groups trivialize the fight (you can do it with only interrupting incinerate, and thats on a 12 second cooldown so any tank can do it).
Now if you have a commando and a scrapper spec scoundrel as DPS, you are -screwed- (Well, its doable...but its gonna be a pain).
WoW proved it was a bad idea to not design all classes to fill a role equally. If it's beneficial for DPS (or healers for that matter) to interrupt, then all classes that are supposed to fill a DPS role need to be able to do the job.
As it stands, Sage DPS has a ranged interrupt. Apparently scrappers do too. Commandos do not. It is a design mistake and will cause problems in the future.
It's not the only questionable design issue though, at least Commandos got battle rez in 1.2. We still need the Rescue ability though to have parity.