You can separate clear reproduction of dialogue from high fidelity?
Please enlighten me.
That's not what's being said, I'm referring to coverage issues in home theater (3.1 and above)
Say you have a home theater with a dedicated center - this is used for dialogue 99.9% of the time. Intelligibility of the center is critical for movies. In-spite of this many living rooms (IME), especially those with lots of seating for children/visitors, have seats far enough off-axis that even some of the best traditional designs have a non-trivial drop in SPL. As such, even if the content is the same the level difference can result in intelligibility issues. This results in complaints regarding volumes from those on-axis v. off-axis. Differences of 3dB can cause potential intelligibility issues, so trying to maintain SPL across seating is a consideration.
An omni design simply helps alleviate this SPL drop. A good 3-way can mirror the spectral content off-axis well, but the SPL may not be sufficient for all viewers. Effectively it becomes a coverage issue. Rooms that have seating at
severe angles, with people unwilling/unable to adjust seating for better coverage, may find a solution in omni designs. When I sold my Mirage's it was to a family with that exact use case.
Obviously since I sold them I prefer other designs, but horses for courses.
I don't see movie sound as HiFi, in general - just part of and usually subservient to the visual presentation.
Sound reproduction can make or break movies. An original score for a climax, an action scene that demands full bandwidth and placement, a chilling monologue from an antagonist. I've had a range of displays, but even those that weren't great I could enjoy. The sound was infinitely more important to me. Good sound to me allows a higher degree of immersion.