RNG with DH and Crits would be a problem for short encounters where getting 1 crit or Dh would make all the difference.

In 10+ minute encounters where we use several skills per minute said RNG in the dps is mitigated.

That being said, RNG during key moments, such as damage spikes can make all the difference. If a raidwide aoe or a tank buster would have saved you and your teammates by having 10% damage reduction, but your "cards" didn't grant you the mitigation when necessary then that's bad design.