Why don't more recordings have soundstage outside of speakers

Same recording...different speakers, even from the same manufacturer will yield a different soundstage in the room. Much has to do with how the crossover is voiced, the size and shape of the enclosure, and the size and type of the drivers being employed.

Case in point. JBL display at CES a couple years ago had 4367 (15" two way with horn/waveguide) $15,000/pair, next to the newly introduced L100 Classic(12" threeway, 5" mid, 1" tweeter)$4,000/pair. Both being driven by Mark Levinson amp, they simply switched cables between speakers.

The recording was Eric Clapton, don't remember the album, but it did have "Tears from Heaven". The L100 Classic presented an image that was in front of the speakers...in the room, if you will. Very nicely balanced from top to bottom. When switched to the 4367, the music retreated into the box with virtually no dimensionality whatsoever. Very disappointing for $15,000...though the bass response stomped all over the L100. Not enough to make me ever want them.

Remove the room and listen with headphones.

millercarbon9,311 posts05-26-2021 5:12pmThere's actually a very prosaic answer to this question. When we listen closely we tend to look in that direction. Ears on each side of the head, duh. When we record we do the same. Maybe there are groups the performers occupy different locations around the room at random. Not many, is my guess. From intimate solo singer to full orchestra to U2 extravaganza the performance always occupies a relatively small area in front of us.

Anything way off to the sides is therefore much more a gimmick or effect than music.  

There. Done. And on to the next question. ....  

Seriously? That's a very myopic statement.

If that qualifies as your definitive answer to recording, you're demonstrating that you don't know very much about recording.