The original motivation is to let arc diff use --lintall by default so our people don't need to pass the argument manually every time.
One solution I can think of is to add a setArgument method to ArcanistWorkflow so we can add --lintall argument in a customised ArcanistConfiguration.
You are probably raising messages at "warning" severity, but want to raise them at "error" severity. See, e.g., here for a description:
Not really, we actually want people to be responsible for the files they changed not just the changed lines.
The only behavior of --lintall is to make warnings act like errors. Just raise everything at error severity to achieve the same thing without patching anything.