Happy that you ask, first of all you are right but not in interlude. Events like CTF, DM, StriderRace, RaidEvent(even with some addons) are the ones you can find and adapt sharred in forums like l2j's about the rest, we'll take care of them there will be no leeching. About mmocore.. well a clean code without useless lines is always better, moreover it can be quickly developed when the code is efficient, when it is well structured and even elegant that makes it in my point of view obviously faster and more reliable.
EDIT: The alternative and not "additional" Crown system my mistake, is a custom instance where as a guild leader you can recieve the castle crown automatically without buying it when you own a castle. and this instance is readable by enterworld, there is also protection and checks to avoid any "bugs"