I agree there are costs but it’s on both sides in my opinion. Techincally, with ESM, a Trusty charm is a supported option for getting things done. We can’t auto yank Trust which is why our code designed to warn users about deprecated series of Ubuntu doesn’t throw alarm bells at Trusty use.
There’s also a question of discoverability. If we were to remove the Trusty charm promulgation (when Juju doesn’t think it’s deprecated especially) then folks wouldn’t find it and think it didn’t exist. The best scenario, from my point of view, is for folks to find it and see it for what it is. An outdated starting point that could be tested and hopefully updated. Encouraging folks to acknowledge that it’s a charm that needs some love and the best way to go is to get involved. Try it out, post your findings, see if it works smoothly, suggest improvements, etc.
Personally I think the hiding it approach lacks the encouragement to get involved and join the community.
It’s reasons like this that have me just holding serve until the new system with its rules come along and shake things up as I don’t think we’ve got great answers in the current pattern.