System accounting can be useful information when you need it for load balancing issues, for example, or tracking down an errant looping script command. Since this is an educational environment, it is hoped that students may enjoy and learn from running these types of programs. For example, the following script can make it appear like you are running vi when you are in fact running some other program you specify on the command line. Any files found in any directory other than the above are subject to immediate deletion. Be nice to the system, so it can be nice to others.
Disk quotas are an attempt to encourage disk space conservation.
Abuse of disk space is expensive, prolongs system backups and restores, etc. There is a killer email virus on the Internet. If I hang out on zuni, no one will know I am there. Besides, zuni is under heavy load from DOS users during school hours and all Unix programs, news, and mail are on hopi, so you will most likely get better response on hopi.