1. I can upload them easily via the blogger app
2. Because I actually think the macro on the iPhone 4 camera is pretty good.
Today, however, I experimented a bit with my "real" camera (a Canon Powershot S95). It´s still just a compact camera so the difference isn´t that big but combined with some Photoshop work the pics came out pretty good.
The question is if the quality difference is big enough to motivate all the extra work...