There are more minute sounds in music (like reverb trails) that need some space to develop and if you’ve got the speakers too close to the wall they get squashed and you’ll lose that sense of space/depth that those signals help create unless your speakers are specifically designed to be near the wall. Pulling speakers out can also greatly help with achieving optimal frequency balance. My speakers are about 6’ out from the wall that for me results in optimal frequency balance along with 3D imaging/soundstage. The good news about experimenting with speaker placement, unlike most things in audio, is that it’s free!
Why does pulling out main speakers from wall improve sound?
Ask my dealer this question and he was stumped. He said it's a good idea but couldn't say why. I see speakers pulled out eight or more feet from the wall in very nice systems.
The drivers are facing forward, and when there are no ports in the back of the speaker so why would it matter?