Thanks. If you're interested in expanding usage of this extension, you could ask someone to make a mwgrep list of wikis where the gadget is used (and act at least on those where it's on by default).
I do think this extension should be enabled by default. Maybe we should
prepare list of projects with no sandboxlink and their's village pumps (or
use tech news), notify them, wait a week/month for objections, if local
(don't want), simply add false line, if global, solve and finally deploy in
the same way we use for other exts. Is there a task?
In another words, why mwgrep wikis when we can just enable everywhere as no
reason why not is there? In same way we force upgrades?
I do think this extension should be enabled by default
That's much more disruptive and best discussed on [[m:Wikimedia Forum]], this task is about maintenance to reduce technical debt (and let's not go infinitely off-topic).