I'm not sure what the cause is. Sure, Net::Telnet will establish the connection, but Expect.pm has all sorts of functions for looking for specific user-defined responses, and automatically recognizes a prompt. If it's a matter of telnetting in, doing an ls, and exiting, Expect is overkill, but if there's an extended conversation between client and server, Expect makes life easier.

-Logan
"What do I want? I'm an American. I want more."