The customizations section is pretty much used as an "other" section as it stands right now. Almost all of the most popular items are shaders but there isn't even a category for them. This is also where people post datapacks now that vanilla minecraft and most mods support them, but that isn't a category either. Despite this, there's specific categories for lucky blocks and building gadgets, out of only 4 total mods with specific categories.
What the system needs is:
-A specific place for shaderpacks, either a category or their own section
-Better support for datapacks, actually auto-installing like mods would be nice but they should at least have a category
-Better support for modern customization mods other than crafttweaker
One improvement could be utilizing the dependencies/dependents system already in curseforge, making projects under the customization section searchable by the project(s) that they're a customization for(if any) as a replacement of adding each mod to the sidebar manually. The one problem with this is mainly shaderpacks, which are mostly addons for a mod that is not and likely will continue to not be hosted on curseforge(optifine). I'd say this should
Another improvement would be specifying which folder a customization is added to. some need to go in a folder to load datapacks from, some need to go into the config folder of a specific mod, some need to be loaded as a resource pack but aren't a texture pack, etc. This would allow customizations to be a tab in the launcher instead of only being externally available.