You're basing most of those on real-world examples, rather than taking the in-game examples for what they're worth. It's the same as, like I already pointed out, looking at the Legion from an NCR-centric position. But taken from a neutral perspective, or from that of the Legion itself, you see it in completely different colors. On the one hand, it is spreading GENUINE civilization, security, safety, and futures to the territories that it collects.
What was Dogtown (Denver) before its Legion conquest? It was a pit where survival was harsh, and prosperity was a delusional fantasy. It was anything BUT a bustling metropolis, and was plentiful in "resources" only in the sense that because of how dangerous it was (like the Glow, but not due to radiation) there was precious salvage that was unobtainable. Did the Legion bring it to ruin? No. It wasn't specified what became of Dogtown, but its survivors were assimilated, which means they were given a better life. True, it meant going from a bleak life of uncertainty to a dogmatic (pun not intended) life of military conformity, which guaranteed your death on some unforeseen battlefield in murky future. But you can't ignore that it granted them a definitive improvement to their standard of living.
Caesar's "faith" in Vegas changing the Legion wasn't mistaken in any respect. For one thing, claiming the city was contingent entirely on TOTALLY besting the NCR, which itself would have involved changing the Legion. This was already in the works by the time of the Courier's involvement. The expulsion and replacement of Malpais (Graham) with Lanius was part of that process. The Legion's forces had to be versatile and tactically adaptive, unlike Graham's approach of brute force and overwhelming numbers. The Legion had to become BETTER than its adversaries, not just bigger or brawnier. (By contrast, the NCR's forces were doing the same thing, only in reverse. They won the first battle of Hoover Dam through strategy and tactics, thanks entirely to Chief Hanlon. Now, because of petty jealousy and blind desire for fame, Oliver has done everything in his power to subvert Hanlon's influence over the NCR's forces, with intent to win the next battle with zero strategy, and pure, overwhelming numbers and force... and astronomical trooper casualties. The NCR is regressing while the Legion is evolving.)
Secondly, Caesar didn't intend to just "claim" New Vegas like any other spoil of war that his Legion had already won. Vegas was going to become the Legion's capitol- "Its Rome", in his words -and they were going to change from a roving horde to a situated empire. Again, this would be physical, definitive change, not speculative. Another facet of this which might provoke further adaptation on the part of the Legion was the technological disparity between the resources of the city and the capabilities of the Legion. This would mean that, while not necessarily abandoning their "reliance on technology is cowardice and makes you weak" philosophy, as far as martial prowess is concerned, it would usher in a technological awakening period for the Legion with respect to their surroundings and their livelihoods. Their culture would change and advance, out of necessity.
You can pick apart Caesar in many ways, but you can't claim that he's delusional, or full of shit. He is a liar in the sense that he plays on the more gullible elements of his armies by creating a false mythology surrounding himself (that he is the son of Mars, and a demigod). However those with a firm understanding of the Legion, or those who simply knew him long enough, are well aware that he is a man, but a very capable one, and a remarkable leader (thus their following him). What would become of the Legion if you spread word that his background was all based on old books? Not much. The Legion had followed Caesar this whole way, not Caesar's image. They listened to him because he was brilliant and convincing. (Meanwhile, the very fabric of lies surrounding the NCR's presence in the Mojave is already causing it to buckling in on itself, due to widespread public unrest and discontent over their leadership.)
When Caesar talks about the philosophies of war, and the fundamental evolutions of societies on a dialectic level, he conveys the presence of a man with a vision and a purpose. He's not spinning words to win you over; that's what the threats and assassins are for. He knows what historically worked and what failed, on a societal scale, and he's taking all of that knowledge, and using it to shape the wasteland how he believes is its best course. He may be wrong, but he has TONS of knowledge and experience backing his convictions, not at all unlike Mr. House (they are the most alike of all the major characters of the game, if not the entire series).
The true faults of the Legion are with its lowest level troops. Men are granted privilege and women are forced into submission simply because the bottom circles of the Legion know no better. Might is right, to them. They have no vision, and their morality is essentially dictated to them. It's entirely true that many of their slaves were "given purpose" by the Legion, but that's not universal, and your everyday Legionary wouldn't know the difference, because that line of rhetoric is pounded into them from day one, not the meaning of it. Finally, the Legion WILL fall apart when Caesar dies. It doesn't matter where he steers them, so long as he draws breath, the Legion will unfaltering follow Caesar. This is good in that it unifies their purpose and they have unfailing cohesion, but it's bad (epic understatement) because that means Caesar's passing is akin to the death of the Legion, itself. All of the Legion's growth and advancements would grind to a total halt. Even if a new leader was appointed with minimal bloodshed, unless he was groomed by Caesar to carry on his vision, the Legion would still change in a way that's most likely a regression from the benefits of its current model. Again, this draws many parallels to the NCR after President Tandi's death.
Once you get right down to it, House's faults are simple, and easy to recognize. He's pragmatic to such a degree that even human life is a statistic to him. He's cold, yet really the best bet for the future of the region. NCR's faults are not as easy to spot, and if you don't pay attention to them, they look like a GREAT future for the Mojave, even though they're arguably the worst. But the Legion is just as mixed of a blessing as the NCR. They bring more than death and despair with their conquest, much like the Unity once offered. Does that make them right? Again, just as with the Unity, most like not. It's EASY to vilify the Legion because the whole Mojave is littered with ONLY NCR-centric propaganda (making Lanius out to be a brutal, savage boogeyman, yet when you meet him he's an honorable warrior who won't sacrifice his men's lives for a hollow victory) and you always have the "they're slavers, and slavery is bad!" argument to fall back on, but these are shallow reasons to blanket the entirety of the Legion as "not having shades of grey". Clearly they do. You're ignoring their accomplishments, their economic prosperity, their cultural richness, and the human lives they're built on when you just look at 2 things and say that the Legion were all bad guys. They're made out to LOOK like it, but that's all.
. But India only profited by the British owning us for a bit. The could have been less brutal about it sure, but now India is set to become a global superpower thanks in part of the British teaching us a lot about western civilization.
Superpower is a meaningless term, just ask our American friends. 
