FSCK after power failure

[STYMA, ROBERT E (ROBERT)]

When Linux boots after a power failure or other
hard stop, the boot process detects that the file system
was not closed cleanly and gives you some small number
of seconds to press the 'y' key to check the file system.
If you do not press the 'y' key in that interval, the
potentially corrupted file system is mounted.  Why is
this default instead of the other way around?