These are very fair points, maybe a reason not to have this feature on by default then.
For me, I work against clear origin/master, origin/master, origin/develop branches at my dayjob, and when I do open-source there is a default branch to work against. The GitHub 'gh' tool defaults to upstream and origin repos, which is why I chose those. But I agree it might not be right for everyone.
Maybe what I wrote in a previous message about making this configurable via 'repo.settings.defaultBranch' (maybe call it 'repo.settings.statusGoalBranch') would be useful, but having it off by default instead of on by default as I originally suggested.
I feel strongly that it should be able to be set be repo-specific (and globally). Having it only per branch defeats a big part of it. Should be straightforward git config to have a repo-wide rule but still allow disabling it for e.g. 'gh-pages', I hope?
Harald