Hey Johann, thanks for sharing your excellent work here. I share your concerns about the limited degree of image formatting available. I've thought about making a proposal for a "photography mode" post option. In such an option, images could be larger, could be made larger with a javascript expand-on-click, and have a dark grey background when expanded. Gallery slideshow controls would be neat too.
I've held off on making a proposal because I don't have the skills needed to build it, and I get the sense the Steemit UI team have their hands full already.
For now, what can be done is turn the images into links to a larger version, to whatever size you're comfortable with, re: piracy. I do this for some of my photo posts, and use a much larger watermark for these.
Your idea of a Photography mode is a great one... I was thinking about the watermark idea, normally do not like to do it - you know the "cut your nose and spite your face" idea (https://en.wikipedia.org/wiki/Cutting_off_the_nose_to_spite_the_face) . I once removed a ugly watermark from a friend's photo (painstakingly rebuilding the image in Photoshop) just to proof a point as he decided to publish large versions of his photos with a watermark on facebook. I prefer to always use small photos, if then pirated it is then at least not print quality. An interface where you have a digital loupe is the ultimate answer, so if you need to proof the quality of the photo, a person can use the loupe to check the specifics. Maybe we need to do it ourselves...