It started as an attempt to make freeciv (based on civ2) more similar to civ3, but there are several features from civ3 that can not be implemented in freeciv, and many others that can not be exactly equal, so it ended as something in between.
Since then, I just try to use in the mod the new features introduced by the new versions of freeciv, no matter if the come from civ4 or later versions.
Contribute, display and discuss rulesets and modpacks for use in Freeciv here.
Anyway, only_killing_makes_veteran is being implemented as a ruleset option, and not as a hard rule, just because some people want it one way and others the other way. Ignatus wanted it enabled, you may want it disabled.