I think people have thought about it, it's just that doing the whole bridge static is quite time consuming, and there hasn't been enough interest in someone taking that time.
It'd also be kind of tough to mix in the Arado jets in since they came in many days after the bridge was captured, so it's kind of like a separate scenario. Tho I could see a cool scenario where an Arado spawns after the bridge is capped and the Germans get one last chance to win/ tie with a bombing run
But long story short, most ppl are focused on other stuff atm. Remagen would be a very time consuming map to do, and there's not much interest in putting that much time in.
EDIT: cool yea they did make one for FHSW;
https://www.youtube.com/watch?v=XiP2IWCMtCY. I guess that has the Arado spawning for Germans at all times. Still kinda a cool way to do it