While I agree with most of your points on Bastion, I don’t like the rework. I don’t think locking Sentry mode behind an ultimate is a good idea.
Recon mode is actually pretty good in terms of damage. It’s somewhat close to Soldier’s damage output. Before his rework, Recon was pretty trash, but the rework really helped out that mode a lot. The part where they took away a lot of Sentry mode’s damage is the bad part of the rework.
I don’t agree that full immobility has no place in this game. I think it’s fine that Bastion is immobile, but he shouldn’t stay in the same spot in Sentry for too long. He needs to move around, or else the enemy team will figure out where he is, and just kill him. Sentry should remain the main focus of his kit, but other modes should be emphasised more than they currently are. Taking away his passive Ironclad and giving some (if not all) of his damage back is the best course of action to make him more viable.
The rework also did quite a number on his Tank mode. It took away his 150 armor, and only left him with roughly 75 effective HP via 20% Ironclad. I agree that it’s fairly weak at the moment, that’s only because of the health issues with it. It does good damage if you can get used to the projectiles.
While I don’t agree with this rework, I do think giving him access to his Tank mode as a normal ability is a good idea towards making him viable. I’ve made a post about a Tank on E rework, going into more detail about all of the changes, explaining them. Here’s a link if you’re interested.