Hate to say this, but how about you "finish" the systems that still aren't finished and squash a few hundred bugs before starting on something new. (there are plenty in the bug forum that are relatively simple fixes)
Then, when you do start work on a new system, you should to talk to the players first before you paint yourselves into a corner with ideas people are going to rail against later. (Refinements) However, you must talk to more than the sycophantic pom-pom wavers, and avoid filling your focus groups with Stratics staff.
Once you start on such a new system, you need to ensure that you don't try to over think it by making it needlessly complex, redundant and tedious. (I'm looking at you, High Seas crafting) If you add new items, especially resourses or consumables of any kind, they MUST be stackable from the start. If you add artifact-like loot of any kind, make sure the stats are something a player will actually desire, not immediately drop in a bin. (Ararat artifacts) If you add easter eggs, leave enough clues that people can find them, or even know they exist in the first place. (golden toolkit) If you add a quest, allow us to keep the pieces of said quest should we choose to do so as deco.
Lastly, if you're going to give us something we've been wanting for years, don't do it in gift form. This only makes it a headache for those that weren't here at the time to acquire after the fact (ie mailboxes), add things as craftables. (this is a major failing of the King's Collection, over half the new items aren't even craftable) Also, don't later add it to the clean up system and call it good. Craftable is always the better choice.
