Also, I am afraid that splitting up contributions in categories will do the opposite of what we want: people will think that code contributors are a better category than conference organizers. And I thought we don't want that.
Ultimately, it is a value judgement who is a valuable contributor, and we shouldn't try to hide that behind formalisms. The process will always be some variant of "Hey, I think Cornelia should be on the list." - "I agree, let's put her on the list."
+1
I recall a few years ago there was a debate about one contributor being moved from Major Contributor to regular Contributor. Adding new levels will ultimately create more such debates, and we will need to be ready for that.
I like Cornelia's categories. Reading through them I recognize that I and many others would be fully invested in the token economy (aka "gold star economy") created therein.
The badge proposal described by Melanie would create similar investment on my part. It also has the advantage that badges can be created on-the-fly to recognize achievements that otherwise defy classification.
But having either such thing would pressure the community to categorize and quantify every unit of work put into it, and then defend those quantities and categorizations when someone feels slighted by their ranking. My fear is that the new burden will fall on people who are already contributing greatly, and thus would be contributing less, and the new contributions won't make up for that loss.