That's a cop-out... There are plenty of cases where you'd want users to be able to choose filenames but not be able to DoS administrators (or scheduled tasks) that run over those directories.
While I guess server software, such as web servers, samba, etc could always store a random filename then create an index for it in a database, that's exactly what a directory is supposed to be doing anyway - and the database probably has the same vulnerability in whatever hash it uses.
So assuming that you come around to the fact that filename hash collisions are a bad thing, it leads us to:
- Directories probably need a random hash seed for their index (one for the whole FS probably won't cut it)
- crc is not an appropriate hash, as even with a random seed an attacker can still cause collisions