Aside from the discussion about their lack of content or whether or not the game presents reasons for the player to join them, I feel the Legion is very misunderstood by players in general.
There's this idea that they're pretending to be Romans, or trying to emulate ancient Rome. They're not. Apart from Roman imagery and names, and the idea of conquering and assimilating other groups of people (which is not at all unique to Rome) they have nothing to do with ancient Rome.
Caesar picked Rome to use as his theme because it saved him the time to create new names and symbols from scratch, and because it was a completely alien theme that he could use to spellbind the backwards people of post-apocalyptic America with as he created his cult of personality.
Then there's this notion that they predominately or even exclusively use melee weapons, which is completely false. Most legionnaires use firearms. Unlike the NCR, they don't have a standard rifle, but instead use a wide assortment of guns such as hunting rifles, shotguns, revolvers and SMGs.
Legionnaires who are only equipped with swords and throwing spears are a minority. This minority includes the iconic Legatus Lanius, who I believe have altered people's memories into believing the Legion are all machete-wielders who rush into melee.
Another thing I think people often overlook is that the Legion consists entirely of brainwashed slaves. From the lowest recruit to the Legate himself, everyone is a slave to Caesar. No one chose this life. The ones who weren't captured were born into slavery. Their entire lives have been tailored by Caesar to fit his purpose and help fulfill his goal, which is to return home and reform his old country. All they know is what Caesar wants them to know.
The guy is so afraid of his legionnaires getting a glimpse of another way of life that he wants Mr. House's technology in Fortification Hill destroyed without even looking at it. He forbids the use of medical drugs so he can awe his soldiers with his amazing god-given healing powers (i.e. his auto-doc). His grip on his Legion and how they live can come off as comical, but look no further than China censoring Winnie the Pooh for a real-life example of a dictator's absurd paranoia.
The problem with Legion is that their idea of pillaging is retarded. What they will gonna do once all resources are already pillaged? They will have no farm, no weapon and electronic factories, no clean water, no medicine...
The Legion is not sustained by pillaging. They control four states worth of settlements, who all produce for the Legion.
