Obito lacks sinister backstory that strongly justifies his mindset (Tsukuyomi eye moon plan). All we knew about him is he had no parents, and the reason he turned evil is because of Rin, the girl that never returned the love back. Pretty ridiculous for an antagonist backstory. Its nothing compared to Sasuke, Nagato, and Madara.
Furthermore, his backstory doesn't reflect properly on his development. That is why he is extremely poorly written character.
Madara, Sasuke, Naruto, Nagato, Orochimaru, Danzo, Tobirama, Hashirama, Kakashi, Itachi, and many more have more depth than he does.