I'm moderately interested in an update-the-wiki effort and very interested in some SCIENCE on the newer world gen features. Does anyone want to start a new thread? I just started playing DF again over the past month after a 2 year long break (4 years since a serious fortress as opposed to briefly trying out newer features), so I don't know where to begin in terms of doing some science on World Gen. I have a general idea of a few wiki topics that could use a bit of polishing: The Raid Bugs are listed at the bottom of the page as a few bullet points, and so I assumed they were manageable, but on the questions subforum, I was warned they are unavoidable and potentially completely game-corrupting so that I should avoid the raid features entirely if I wanted my fort to last. This could be further emphasized to warn players against corrupting their save files. Similarly, the stress page mentions bugginess, but doesn't properly describe how completely game breaking stress is over the long term. Other topics, like World Activities, need more science done... Perhaps it makes sense to wait on the next big release and then make a collective effort to document things properly with it?
To answer the OP's question I started playing back in 2010 or 2011 (I can't remember exactly and I've changed computers so I can't simply check DF version number), and as I remember it, Elf Diplomats which demand tree cutting limits were completely missing for a long stretch of time (4 years, or 6?). They are present in the latest version but it looks like their tree cutting limits have not been adjusted to be harder even though multi-tile trees now exist.
I can also recall a stretch of time were wagons didn't exist/spawn properly... one of the .31 versions maybe?
So Toady adds and takes things out as bugs and new features demand. Overall, I don't think any removed feature is worth going back to an old version of DF for... many of them were bugged, or placeholders for better features. Even if something was genuinely interesting, other more interesting thing have been added since.