Noob question - Raise Spectre quality

Sorry for the noob question but I do not understand why you would put quality on Raise Spectre and Animate Guardian gems. Raise Spectre says Minion movement speed is capped. Both gems add more minion movement speed as quality goes up. Please help me understand why you would quality these gems.

I am currently running the Carrion golem build.

The cap is high.
Most of the time the spectre is far below the cap, so increased speed is better.

For Carrion Golem, the quality increases its life and damage, a no brainer bonus.