ur a wild man, sunny004
Overwatch is a game where your team has to support one another to be successful, things have to flow smoothly and teams need to watch each others back. Bastion doesn't really do that without a team dedicated to helping him. The way Bastion plays is sit in a single spot and shoot shit, which he does very well. Generally you want a Rein shield in front of him and a healer supporting him because he can't heal himself against a team with even a quarter of a brain So that means you're already 3 characters dedicated to a certain strategy, which doesn't work in qp or comp because communication isn't a strong point in public matches. However, when teams are dedicated to helping the bastion do things, the bastion does those things fairly well if the bastion player isn't a dumb dumb. I don't believe bastion will ever be a staple on a competitive team simply due the fact basically the entire team has to support it. Bastion is crippled in the sense has to set up to do the most damage, and he cannot move while doing that damage.
Another factor is heroes like Genji and Tracer existing, and a plethora of players are fantastic with those heroes. In a meta like we currently have bastion will never do anything because they exist, having to remain in one place is such a hinderance in a game that has so much movement and team fights