UTI files “define” the items (what their properties are, if they grant bonuses, etc…), including their appearance (that’s where the mdb are used). So, if you get rid of the uti, you’ll only have the models of the armours, and the PC and NPC won’t be able to don the armours that were made through the uti files.
Unfortunately, you can’t put folders in a hak, only the content (anyway I never succeeded).
4760… It looks like it’s goodbye to the UTI, I only use the appearance and change the properties etc. myself. Shame about the folders in a hak I thought that would be the case.