Bradley Cooper is way too young and good looking to play a washed up singer

Yes Cooper is a good looking guy, but anybody can be a drunk. It was never really addressed how long he was a star, but even after 10 or 15+ years a guy in his early 40's can be washed up if he's been constantly working hard and partying harder

There are plenty of young men (and women) that have drugged and drank their way out of their careers and often their lives too..
Consider the "27 club" (musicians/celebrities that died at 27) or Elvis Presley that died at only 42..not even counting the many stalled careers from substance abuse.
There's plenty of money and drugs on demand and people that turn their heads when the alcohol keeps pouring.

The same was true of Fredric March and James Mason, who played the same role (except as actors, not singers) in previous (superior) versions of this story.

He's 43. How is that too young to be washed up? Most singing stars are way past their popularity by that age. If they drink/do drugs, they can easily be washed up.

Cooper is forty-four. Elvis Presley, one of the biggest pop stars of all time, was washed up by the time he was in his late thirties, and died at forty-two.

There's a lot of good looking people who don't make it and never get famous. There's a lot of good looking people who do get famous and do drugs. It's a cliche.

He’s not that attractive

Nah he was perfect for the film, the guys a great actor when given the right material. He played the rock star who's lived a tough life and the excesses to a tee. Remember a lot of these washed up singers were/are good looking, look at Jim Morrison for example.