Since I mentioned volumetric fog I think its a good example of the past issues with the roadmap. It got a very large amount of votes. Sat around showing backlogged for ages with few clues as to whether it was being developed. Then showed up as being under development last summer, causing me to get excited. Then it got backlogged again and little was heard about it until it showed up in commit in the month or so before 4.16 preview was done.
Reviewing history, it was useful for me to know that lots of people wanted the as I did. It was useful to know it was under development, and to be told when dev on it got somewhat paused again. It would have been very useful for me to know that dev on it had resumed and that it was planned for around 4.16 at least a month or two before I was actually able to find that out.