I think he was referring to the ability for players to save and re-use their own created characters across many different campaigns, not whether or not the GM could export/import created NPC's.
Well yes obviously. Oops.Although i quoted i was misreading that.
A system like NWN would be an option. There was either a server char vault (player can't locally edit char) or local char vault (player can import from his locally saved chars).
Importing all kinds of different player chars into the campaign can be also a headache for the GM. Too hard to control level differences, items etc. I personally as GM would always prefer to level and develop just inside the campaign.
Maybe templates for the looks (hint: steam workshop prefabs incl. mods), even though they are made fast imho, could be nice. Knowing your blueprint, leveling up should be fast.
I agree the possibility should be there, but restrictioning options or delete all XP / LVL / Items function might be handy then.