That's true about Sami/Cody and their popularity but it takes two. I don't believe they are as popular if the foil isn't Roman Reigns. If Cody comes back from AEW and he's gearing up to face part timer Brock Lesnar... I'd say nobody cares.
Also, The Bloodline story was great when the focal point was Jey Uso vs. Roman. It was getting a bit stale until Sami Zayn got involved but all in all it's been good from the beginning.
I think CAWdy's story is the same with or without Roman.
Sami's rise needed Roman to play off of, but it goes both ways. He injected life into the whole Bloodline angle, and he was the dude really moving numbers if you look at the Smackdown quarter hours over the last 6 months. More than Reigns himself.