same should be asked for anyone who supported caesars legion
caesar's legion is horribly fleshed out in the base fallout game but blame Bethesda.
sawyer's story gives them more backstory and why they're this way but it's still poor justification. then again they're dirty tribal scum so it's expected.
also the graphics in new Vegas are objectively better. the word you're looking for is aesthetics... which is the only decent part of 3.