I don't think you understand what the phrase "artistic integrity" means, on a very basic level. It has nothing to do with not using assets others created, for starters.
It's also kind of funny because codex entries have often been illustrated with slightly modified stock art and what are basically screenshots. It's posts like yours that make me wonder if anyone even played the previous ME games.
I mean, I opened the menu at a bar in ME2 yesterday, and it literally had a photograph of food, clearly from the real world, at the top of the menu. Definitely stock art or googled art. But apparently this is all new and shocking.