Mr Krepe said:
If Caesar got the idea for legion from some history books, why didn't he get the idea to preserve towns history and culture.
Probably for the same reason the Kings got the look of Elvis but didn't even know his name.
As Obsidian devs have said (Avellone?), Caesar appropriated elements of the Roman mythos to serve a purpose. When somebody approaches a subject like that they cherry pick what is relevant and leave the rest.
'Course, those are two separate answers. However, between the two, I was able to reconcile historical discrepancies.
My thoughts on the Legion:
I started playing New Vegas late (I waited for that last patch to drop 'cause I wanted Veronica's bugs ironed out). I was expecting to find the legion "goofy" based on all the discussion around here but, after reflecting on them a bit, I found their presentation very smart. Sure, the Roman stuff seems a bit ill placed at first but, from a development point of view, it really was the most inspired way to create a joinable faction that preached racism, murder, and fascist beliefs
in a mainstream videogame. Yes, groups far worse get presented in games but rarely are you allowed to view them in a positive light. To do so is to give tacit approval to such ideologies and the smartest way to dodge that bullet is to keep a benign historical example squarely in the audience's frame of reference.
This is probably why they opted for the Romans over the Spartans (though 300 has certainly helped their image over the last few years).
Getting back on Topic:
I too lament that the Legion were such a crappy faction. I really wanted to keep an open mind and didn't chose to side with the NCR till about 50+ hours into my session. It just seemed all the missions were NCR -- all the people I met who helped me out were NCR.. I could find no in-character, role playing reason to continue my neutrality, especially when I'm running radio codes across the Mojave for NCR technicians.
The game needed either:
a) A Dragons Age-esque approach to the beginning of the narrative (i.e. different starting locations / scenarios.. though I don't specifically mean origin stories).
*or*
b) More legion territories, towns, examples of their social philosophy, legion companions and -- most importantly -- MORE MISSIONS.
About the only positive thing I stumbled across in my first 50-60 hours of play was Cass' commentary that the Legion protected trade caravans better than the NCR. Still, even this was presented from a companion with deep antipathies against the Legion.
Hell, you wouldn't even need to make the legion balanced from a cultural standpoint: make the legion an easy means to wealth and power (i.e. actually allow the player ease access to weapons, caps and maybe even influences over game play that an NCR aligned player lacked). Dangle a carrot, for goddess' sake!