I'll sell you on him. Here's what Bain brings: The most pressures of college football rusher in a single season since 2017 (83) and the versatility to line up wide, over tackle, or as a 3 technique.
To me the anomaly already happened with him being by far the best defensive player in college football last year. Its not like there are short arm rushers like Bain dominating college every year who get to the NFL and can't play. The arms issue is more of a theoretical cap on his ceiling than a sign he can't play; IE he won't be Myles Garret. He's still universally considered a top 10 pick, that wouldn't be the case if scouts thought his arms meant he would be bad.
Its the same argument between Aiden Hutchinson and Travon Walker a few years back. There was a ton of talk pre-draft about how Hutchinson's arm length was supposed to limit him in the NFL. But now (despite Walker developing into a good player), everyone recognizes that Hutchinson should have been taken first. Bain's wingspan is .8 inches shorter than Hutchinson's. Is that .8 inches the breaking point? Are you willing to pass a on a potential game changing pass rusher in favor of a RB/RT/Simmons repeat because of .8 inches? His wingspan is .125 inches shorter than Aaron Donald's.
So what do you want? The project, or the game wrecker? Every year there are "project" prospects with ideal measurements like Reese, and prospects without the measurables with polished technique and production like Bain. I like the hit rate for the "Bain" archetype far more.
Right now every fanbase outside of the top 5 is salivating at the thought of Bain falling to them.