A resounding YES to a greyed out appearance by default.
I would be happy if it was inactive until specially enabled (once only) in the advanced options.
YES for a default of backup, so long as there is the option to negate backup.
That option could also be suppressed in the advanced options so beginners would always have a backup.
Almost every time I run the registry cleaner,
the only thing I see are "Unused File Extensions".
These are Open Office data files which when clicked do not cause Open Office to open.
I never click them, because I use the portable version of O.O. and select the files via its GUI.
I never need those extensions registered - it is junk information.
No way that I would ever restore a backup of that registry junk, so any backup *.reg will be junk.
... System Restore Point ...
I insist that the System Restore MUST be a single event,
never repeated until CCleaner starts again.
After the backup and the cleaning of the registry there may be more "issues" exposed,
and a further 55 MB R.P. can be of zero benefit - it is junk.
NB 55 MB is my experience with XP - I believe your mileage may differ on Vista etc.
CCleaner should be the enemy of junk - not its creator ! !
Alan