I think Bastion should stay in the damage role, it’s clearly what a killer-turned-good robot was designed to be best at.
The problem he suffers from, imo is he is not very flexible for a transforming robot.
When his team protects him then he gets a lot of value in that particular role of providing suppressing fire but if his team are unable or unwilling to protect him then he simply gets less value than just being a different character.
If Bastion is to become a more legitimate pick outside of the ‘protect the robot’ mini-game then they need to provide him with more tools for outside of Sentry mode.
I actually think his Recon mode is pretty decent but when it comes down to it he has no mobility and his ultimate is sometimes just a loud noise that says ‘You are now safe to kill the Bastion - Block with one tank to win the fight and then never let Bastion setup ever again’