I would have to agree with @EmperorDitto here. The fact that Roblox has already made the decision to extend the UGC program out publicly available for almost all, I believe was their part in enhancing and diversifying the Roblox catalog, noting that even with the current state of the catalog there are people who exploit certain bugs or glitches to their advantage for unintended purposes that Roblox had decided to make User-Generated-Content production publicly available.
I doubt Roblox would create a transparent accessory feature just yet as it can lead to more issues that are just not worth it as of now that have also been mentioned by @Abcreator like moderation of these items, “expensive rendering”, and games that can be unfairly or unintendingly played of the creators purpose. Maybe in the future there can be implemented a better system for semi-transparent items, as for now Roblox has better things to be worried about and should firstly remove or fix whatever method the “exploit” uses to create transparent items, as the catalog is rapidly being filled with them.
Lastly, I do not believe it is game developers responsibility to fix items that creators are making with this transparency “exploit”. If creators are using ways unintended by Roblox to create transparent items then they should be removed and not be extra weight put on developer’s shoulders. Roblox’s decision to publicize creation of accessories, bundles, and more I believe was a good decision for Roblox itself and it’s future, but has proven to not be perfect because of the constant glitches, bugs, exploits, debates, arguments, and whatnot. It is not time for Roblox to allow everyone to make transparent items, and rather should fix this “exploit”.
TL;DR: Patch/remove whatever method is used for creating these transparent items, do not create publicly available transparent items YET, and it is not game developers’ responsibility to fix these items in their games.
Roblox, please fix this!