I think we should look at use case scenarios to figure out if there's actually a better way to approach the concept of having libraries with addons, all possible from a single master patch that senses which samples are present. For example, imagine creating a drum library that could be expanded with additional addon packs without needing to download a patch that addresses very specific ownership conditions (e.g. you own these two addons, but not this one…)

Having a missing samples indication is very important, though. If there are samples that are corrupt or in the wrong location, it's important for the user to know upon loading the library. That way they don't start playing and wonder why certain notes aren't playing.

Speaking of which, here's a semi-related request: the ability to purge single samples. Kontakt can only purge samples on an entire group basis. Maybe it isn't necessary with the whole containers thing, but just having more control over things like that would be a big improvement. It wasn't until Kontakt 5 until we could check the purge state of groups, even though you could purge groups via scripting back in Kontakt 4. So the lack of complete "getters" and "setters" for everything is one of those nuisances in Kontakt.