But once you create the structure to hold your photos (a one-time thing), posting is easy. I like my photos organized - that is why I create a more complex "category" structure to be able to put photos in locations where I'll find them much easier than if they were all in one bucket. I often re-use photos I uploaded here and it makes sense to me to have them organized (just like I had on Photobucket).
Another benefit is that you can now go to your photos or your gallery to edit (rotate) that photo so it is upright. You could not do that to photos attached directly to a post. And of course you can point someone to your gallery and to a specific category containing all related photos. Another nice thing about hosting photos in the gallery is that you can preview your post and it will show photos (previewing a post with photos attached to a post did not show them).