Find me one piece of art that actually resembles Iris, rather than a similar-looking older sister that looks as attractive as you think she is.
No one draws her as she is; who appears, far as anyone can reasonably assume, a 16 year old girl. Yes, I know Vetex said she was 18, and that’s not too far of a stretch, but let’s be real; that wasn’t your first assumption. Her supposed age is just a weasely lie to appease the fanbase. Also, 99% of Iris drawings show her with a clear face, no freckles in sight. It’s literally a key part of her design!
The collective obfuscation of these details are necessary to be attracted to this:
Look at this image I found on Google. Does it make her look different from how she did in game? No. Is it attractive? Yes. The same cannot be said for fanart of Iris, which almost without exception makes her look older.
The final reason why Maria is superior to Iris lies in the unique mechanics of her boss battle. Her ultimate attack, specifically. I’ll leave you to figure out the implications.