The surround.vim plugin masks the 's' command in visual mode, replacing it not by an awesome feature (like many other key combos), but with a useless ;echoerr stating that I should use 'S' instead. I definitely did not want to press 'S' instead, since pressing 's' in visual mode is a standard Vim command (see ':help v_s'). I know it's the same as 'c' (see ':help v_c'), but it's hard to change many years of muscle memory training. :)
Anyway, I hope you agree masking normal Vim behaviour with just an error message (and not with added features) is not intended behaviour, so please remove the :echoerr. Thanks!
It is an unfortunate side effect of the intended behavior of prominently notifying users that a very popular map has been removed. The map is being removed for the exact reasons you give. I'll kill the error map before cutting a release (that's long overdue), because at that point hopefully release notes will do the job.
In the meantime, if you're clever, you can use a VimEnter autocommand to nuke it at runtime.
So, you consider overriding a built-in with a non-feature (namely an error message) better than having a duplicate keymap to a real feature? :)
With the old map, I got bug reports. When I killed the map, I bug reports about that. So I put in a removal notification, and what I do I get? Bug reports.
If you're so eager to get it removed, go chase down the commit where I first added it, and tell me how much time has passed.
Remove s warning