I have had the same issue.
I have been with Apple for numerous years because of system stability and robustness.
The possibility to be able to change icons was one thing i appreciated.
I clearly understand the need of SIP.
If I am not wrong SIP is for System Integrity Protection.
But the decision by Apple that changing icons can have an impact un System Integrity is rather puzzling.
Keeping a visual identity is maybe interesting from a commercial point of view but pushing it to the level of not being able to change icons is starting to fringe with dictatorship. Icons which by the way have not changed for a while and people (including me) are getting rather bored of the stonewashed jeans color icons.
If for reasons of keeping/imposing a "Mac" visual identity on the system, Apple which to restrict possibilities to change icons (system icons), maybe at least they could propose a limited set of predefined icons amongst which a user could choose, each of course following the graphical charter of Apple.
At least that would be much more agreeable that just a "NAH YOU'RE NOT ALLOWED ANYMORE".
"Starting Restricted, and softening out, always works"
"Starting Soft and Restricting after, always fails"
