Interesting that your experience is so different. What sort of music do you listen to and what sort of concert hall? Which omnis have you listened to and how have they been set up?
I think that this is really an area where personal preference takes over. And it's great that we have manufacturers catering for all tastes.
I prefer narrow dispersion and/or treated early reflections because that way I can listen into the recorded spatial cues of original venue without my room overlaying its own acoustic footprint and also affecting image focus.
But I agree that omnis produce a more immersive experience.
Whathever floats your boat.
2-channel stereo over speakers is fundamentally flawed in its inability to recreate the original soundfield: both direct (instrument or vocal) and reflected (room cues, audience noise and handclapping) sound are created/reproduced and reach the listener coming from the same sources located in front of the listening spot.
Stereo creates the illusion of left to right and azimuth/depth location of the phantom sources but venue cues that should be coming from the sides and even from behind the listening spot are also generated in front of us. (I am referring to live unamplified acoustic music performed in a space with natural acoustic characteristics)
On top of that the listening room is creating its own reflections and the overlaying of original cues and our room's acoustic footprint makes the recreation of the original venue ambience confusing.
A livelier room will produce more envelopment or immersiveness (and help the speakers disapear as source) but it will also have a negative impact on the audibility of the recorded cues and thus lower fidelity.
But, as with other aspects of sound reproduction, whether one chooses a deader listening environment and/or narrow dispersion speakers or a livelier room and/or wide directivity transducers is a matter of preference.
