well the same applies to having an IndexDocValuesConfig.
If my implementation doesn't use packed integers, it doesnt make a lot of sense?
So I think it would be best if this was only a parameter to this particular implementation... otherwise we end out with a ton of options across all possible implementations, which won't make a lot of sense at all.
I think at the end of the day, we should imagine having tons of implementations for the different index parts (look how many term dictionaries we have), and let impls have their own parameters.
If someone wants to toggle these crazy parameters, thats something they can do in their codec definition. For solr users etc, thats something they can tweak in the xml on a per-implementation basis just like when they provide crazy parameters to various tokenfilters in their analysis chain.