No, it is still configurable. You can specify in your opencode.json config that it should be able to run everything. I think they just argued that it shouldn't be the default. Which I agree with.
No, the problem is that when logging in, the provider's website can provide an authentication shell command that OpenCode will send to the shell sight unseen, even if it is "rm -rf /home". This "feature" is completely unnecessary for the agent to function as an agent, or even for authentication. It's not about it being the default, it's about it being there at all and being designed that way.