Currently the system check issues a warning when the
piwik.js file is not writable.
On the other hand:
So because of these two points I propose that we could:
In the future even some core features might not work as expected.by
In the future, some of your plugins might not work as expected.or so
Reported in #10706
We should still warn because we eventually would like to refactor all plugins and make more use of it. Otherwise people will never make it writable. Also it is only a warning, not an error so people can ignore it if they choose so. It will save us a lot of pain over time when it is a warning and when people do make it writable.