Genuine question as you seem to know your stuff: is there a particular reason why you don't own an SLR or high end point and shoot style? Is the SGS4 camera particularly good, or is a more of a pragmatic reason?
I use to have a DSLR with some expensive lenses. My gear was worth almost £2,000. The only problem is that its a little anti-social to go everywhere with a camera bag and a tripod. The female doesn't really like it and to be honest, neither do i [unless I'm somewhere where there isnt anyone round]. It attracts too much attention and you can look like a ****. It also distracts from the experience of a day out with your other half.
The good thing with a camera phone is its discreet and very fast. Point, shoot, end of! You do the editing later back at home.
I like the S4 camera a lot. Its not the same quality as a dedicated DSLR (but then phones will never reach that level) but it does capture good detail and accurate colors (some argue they are saturated but they are realistic. People thing iPhone5 takes better pictures but only because it boosts the colours).
Its just more convenient and i trust the S4 to take pictures which have everything you need to edit to a very good quality. I wouldn't even attempt it on my previous Nexus 4 or iPhone 4S.