Some people just like the idea of being above someone else.
They probably like to know that they have control.
Some people are also really pathetically lazy and would do anything to get Admin Teleport.
Mind you, I have Admin on a few different servers, so I can easily Teleport.
However, if I'm on a server that I don't have Admin on, I do feel rather slow not being able to move around as fast. Even so, I still wouldn't join a random server and just start asking and begging for Admin.
I also think that newer players don't quite understand how much of a responsibility and power comes from Admin. They probably think of it as a nice handy thing to have. Something to make it a bit more fun. Which is probably why they ask for Admin, since they don't realise that giving Admin to someone does put your server at risk.