...because the rest of costumes with no effects will be open for malangdo enchants. You keep talking like costumes with effects are the one and only option for all classes. Wrong. I certainly don't see many people defaulting lamps, or full moon, or dragon helm. Guess why? malangdo enchanted costumes are way more versatile, and they'll still be wanted because kro will keep developing new effects for them. I don't know how you can't see this.
To make my point clear, costumes that already have effects such as tarnished lamp shouldn't be enchantable, they should have their specific effects and that's it. The rest should all be malangdo enchantable, so you're free to wear whichever you want.
So where's the freedom in picking whatever costume you want if certain ones are locked out of getting enchanted?
"Sure, you can enchant costumes, but if you want to enchant the costumes on this blacklist, well, too bad you're out of luck!"