A ResourceLoaderImageModule is needed to ship icons in MediaWiki so if you need icons you will need at least one additional ResourceLoader module. In many situations this should be unnecessary. For example a skin is already likely to have two modules - skin.name.styles and skin.name.scripts. Either could ship those icons.
In MobileFrontend/Minerva this problem is well illustrated - In Minerva there are 8 modules shipping icons. The skins.minerva.mainMenu.icons module however could be merged into skins.minerva.mainMenu.styles and reduce the ResourceLoader modules by one leading to less modules overall and a much smaller startup dependency tree.
Please consider allowing ResourceLoaderFileModules to support icons so that we can reduce the amount of modules that are needed.