That in no way answers why such items should be liked or disliked, or whether the devs have or should have a specific decision-making criterion other than the number of "likes" and item receives. People may love the taste of asbestos yet it's still not necessarily a good thing to feed them, and governments may "like" the idea of an aggressive eugenics policy there sees to be more at issue than popular flavour of the month politics.
Sadly the world is built on opinions.
In your
opinion full roman legionary gear would add to the mod and be great fun, in my
opinion it will look downright silly to have warriors from a thousand years ago fighting alongside me like this is just an average day on the
medieval battlefield. (If we are to infer a time frame for the mod from the weapons and armor present then it would be about 1000-1300.AD).
If Roman Legion armor/weapons were to be added what would justify it? The fact that there are ninjas, samurai and vikings so we may as well add romans? Did these guys just step out of a time portal? Are we in some kind of valhalla blessed/cursed to fight warriors from all time periods for all eternity?
If we are in a fictional setting (Calraidia) then Romans would be something akin to the old Calraidian empire which is referenced in singleplayer, in that it is long gone. My point is the further you stretch the timeline the more and more ridiculous the explanations you have to come up with to justify it.