Difference in how I pack my camera bag, lies in whether I'm shooting for me, or a gig for someone else. If the former, I'm happy with whichever of my film cameras catches my eye, and no more than one prime lens usually. If the latter, I shoot with a dslr and a zoom that covers focal lengths from 24mm-135mm, with a fast prime to be used if needed.
From what I can see people vary wildly on this one, with most preferring the choice and flexibility of a kit to cover most eventualities, or else preferring the liberation of a simple, spartan setup.
I fall into the second category, preferring a spartan setup, with my personal shooting being an extension of where I am & capturing that. I tried the bag of kit approach, and a lens covering most focal lengths, but it didn't fit my shooting style.
Different strokes for different folks, I guess..