I used connectors on my QS4 installs & had the same issue.

The main reason I used them was that with 12 gauge wiring the cables are so thick that you're never sure if you have a solid connection into the speaker (or the receiver for that matter) without them.

Plus, it makes for a much cleaner installation - I put wall jacks with terminals behind each surround and then made a patch cable to run from the jack to the speaker.