Caching resolutions can be a nice thing, and having in one place can be useful so that the throwing away the cache can be done consistently for all apps when useful (you likely should clear the cache when switching networks, or when the user asks you to), but none of that means it should be a kernel service.

If there's enough volume of requests that a kernel level cache meaningfully improves real world scenarios, something is broken in those scenarios. :p (but I think you agree with me)