domain expired and taken

I was just wondering why the internet domain name system has to tell people when domains expire. Is it technically possible to just delete the domain names from the name servers?

I had some stupid domain names that expired, and those guys the run the search portals took them. I am not real upset as I didn't care to much about them, but it bugs me that the dipshits probably wouldn't have ever thought of them, they just saw they where expiring and they grab them. Using some script or something.

So why do we use the system where it ADVERTISES to the world when a domain name expires to everyone? Seems a little ass backwards.