Those are way to generic to be made global without a real discussion. If they have been checked into 8.1 then expect them to be backed out as soon as I need to do a dist.
Well, they currently are not referenced from within the rest of Pike, except through their __builtin.* references. The global namespace usage will only be used from userspace. So if we decide to move them elsewhere, that's fine. It's just that I myself couldn't come up with anything better than simply a global type; anything else seemed silly from a user standpoint.
There are other sets of basic types. Standards.BSON.Timestamp, Standards.ASN1.Types.UTC etc. Serializing and deserializing data is a recurring theme, so we should probably spend more time thinking on it on a higher level.
Right now I would prefer to not compile and put that code in the global name space every time Pike is started. Perhaps put it in Val for now.