Unfortunately we believe the icon change is essential (and hard to avoid…). It makes it clear what files are encrypted.
It is also hard to retain the original icon, since the icon is normally associated with the extension (.docx, .xlsx, .pfd, .png, .axx) etc. and this changes to .axx for all encrypted files regardless of the original file.
The use of so called icon overlays is possible, but complicated and actually never really works 100% so we don’t want to go that route.