Particularly when riding off-road (but on road as well), the additional leverage and stability afforded by wider handlebars dramatically improve handling and control, especially while descending and climbing. An interesting parallel can be made with mountain bike handlebars, as an example - 76-80cm wide handlebars are now common even though almost nobody has shoulders that wide and it was not until a few years ago that people started realizing that wider was really helpful.
If you haven't tried a wider bar, we highly suggest trying one out - the difference in effective arm angle is negligible, but the effect on control and comfort is dramatic. Very few people want to go narrower once they've tried a wider bar.
We generally recommend that people try a bar that is wider than they might normally use on their road or gravel bike especially if that bar has no flare.