Well, with the original RAIDERS, I actually do think it was more about the overall quest -- hence the title, which refers to ALL the characters. (I'm going to ignore the rechristened "Indiana Jones and the...", which in my eyes looked more like a marketing ploy for the film's home video release than any creative decision. Indy is, after all, a raider of the lost ark himself.)
The sequels became much more Indy-centric, due to the film's and character's popularity. In fact, I think it's only in RAIDERS that we see a lengthy scene NOT involving Indy at all: Marion's banter with Belloq inside the tent.