The project itself is really ancient, it started in 2006 by frjo, in Drupal 4.7, and the same code has evolved until Drupal 7.
I took co-maintainership of the project around 2009-2010, when I met with lut4rp, at the time the one maintainer of the project; who made a rewrite to modularize it at the start of 6.x-2.x.
At that time we were still using CVS officially (and some of us git locally), and we were thrilled to receive and integrate a patch from merlinofchaos, that extended the module a lot, and make it more maintainable.
With the past of the time, I became the only active maintainer of the module.
At the start I was pretty active as a maintainer there; but over the years, I have not been responsive enough, especially around the D7 port.
During that time the community provided several patches and finally amitaibu created a sandbox, that I end up integrating into the project.
Also, I managed to write another submodule, vud_field, in that process.
For me it was clear, I advocated to remove vud_node, vud_term, and vud_comment form the project in favour of vud_field.
From my perspective it was more beneficial: (a) vud_field provided mostly the same functionality on nodes, taxonomy terms, and comments; but also (b) provided voting on any entity, embracing D7 new APIs; and also (c) made things more maintainable.
Sadly, the removal did not happened at that time, and that was one of the reasons why D7 version was never out of alpha status.
After quite some time of inactivity in vote_up_down, this January, I started to port the module to D8, but I only started: only 4 porting commits got into the new 8.x-1.x branch.
Then, I decided to add a GSoC project as student's suggestion to port Vote Up/Down to D8 for this year.
In preparation, this week I have branched out D7 into two different versions 7.x-1.x and 7.x-2.x, adding respective releases to make things more clear:
Hopefully one of the students proposing the port to Vote Up/Down to D8 gets accepted.
It will be great to see the module active again!