I feel like some of the writers, especially Chris Avellone with his goofy Ulysses plot, leaned a little bit into a "both sides" type of storytelling. For better or for worse. Sometimes it works, sometimes it doesn't. My understanding is there was supposed to be a more fleshed out Legion storyline, with more stuff you could do for them and more involvement in Legion territory, but they ran out of time. It's true that the Legion is supposed to be evil, but all of the options seem to be set up as evil in their own way. That's part of why New Vegas excels though and still has vigorous debate to this day. The game lets you decide what the best course of action is. I'm guessing they wanted to give certain players a morally complicated reason to side with the Legion, but because so much stuff got cut, now it would make no sense at all unless a player was just being a completionist or wanted to be an asshole.

There are two otherwise neutral characters who defend the legion: Raul and that one trader you meet at the Legion camp. Raul talks about how he prefers the Legion's organization over the raider tribes that used to live in Arizona. The trader talks about the Legion in neutral, formal terms as business associates. That always felt like remnants of stuff Obsidian never finished.

Don't get me wrong either, the writers set them up to be a fascist cult, but I've always felt they wanted more nuance than that. If I'm being generous I'd say they wanted to set up the NCR and Legion as being equivalent to one another in terms of how fascist they are, but ran out of time to flesh out either perspective. Then Avellone swoops in with the Ulysses storyline to fulfill their attempts at equating the two big factions, but it always fell flat to me. Especially because the other DLCs are absolutely beautiful and memorable compared to Lonesome Road.