From my understanding, namespaces are on the same list with enums of things that the developers regret ever adding to the language but can't take out without breaking old code. Namespaces also at least have the excuse of being a "necessary" jQuery-era "Production pattern" in the land before ESM was standardized and somewhat relating to the similar syntax sugar of import/export when generating AMD, UMD, and CommonJS modules.
So too are "experimental decorators" another thing that some of the developers seem to list as massive regrets. That example is even so much worse than namespaces because it wasn't justified by existing patterns used in Production JS at the time and that they even believed that requiring a compile-time flag with the word "experimental" in it would stop developers from using that compile-time flag in anything destined for Production usage. (Seriously, we all should shame the many projects/companies that did that.)
So too are "experimental decorators" another thing that some of the developers seem to list as massive regrets. That example is even so much worse than namespaces because it wasn't justified by existing patterns used in Production JS at the time and that they even believed that requiring a compile-time flag with the word "experimental" in it would stop developers from using that compile-time flag in anything destined for Production usage. (Seriously, we all should shame the many projects/companies that did that.)