Custom data (Multichoice options) should support hierarchy

I need to "tag" new organizations with Tags and a Custom Field (multichoice options). The problem is that those multichoice options have grown to almost a thousand items and it's very hard to operate with the application.

Just to give you some background info, I have to assign "brand names" of products to all of my organizations. Since these items seem like their number will keep growing in the future, is there an option how to control such a huge number of elements?

I guess that hierarchy (like now in Groups) won't reduce memory leaks for displaying pages, but at least it would be much more "readable" for humans.