Some extensions add options onto other modules. (Standard -> Inventory, as an outdated example). You obviously couldn't do `XM.Inventory.options = [` in both places. And you would need to put in more conditionals if you weren't confident in the load order of the extensions.

I think we should be pretty confident in the load order now, and we can also be confident about extension dependency management. So I would say it would be okay if in the extension itself you put in `options = [`, and in add-on extensions you can use concat. No need for conditionals.