People who work on Halo probably make more money than programmers working at smaller companies. My guess is they get performance and sales-based bonuses on top of their salary. That's fairly standard in the industry. Unfortunately, big budget games usually translate into a more conservative creative approach. Nobody wants to be the one responsible for killing the golden goose.
There's more creative freedom with smaller developers, but budget and technology are often lacking. You can sneak in more original ideas, but you don't have much time to implement them well.
Of course, there's always the reality that most of the gamers out there aren't interested in games as an art form, and are perfectly happy to be playing a slightly graphically superior version of last year's hit. That's the sad part.