I believe that these options must be included in the next update of wordpress.
Am giving you some examples to understand what am saying.
If someone want to put a photo in the text or make a gallery of photos automatically three different sizes of the photo will be created.
That aint logical, we are waisting space in the server for no reason. A photo in a post it would have one size, so the rest of the sizes are needless. The same thing goes for the gallery, only the thumbnail is usefull and the original photo when someone clicks the thumbnail to see the photo. The rest are useless.
So, when we upload a photo, it shouldn't create automatically various sizes the we setted, it should show us the options that it has. Then we would have the option to choose specific sizes that we want to create from the original photo.