Whats the deal with truck tents?

Just curious why some of you guys choose truck tents over just pitching a regular tent. To me it seems like too many disadvantages and hassles and wasted bed space for camping gear etc. Please don't get me wrong, just wondering what am I missing. They do look cool though. I also noticed that most of them are used in the desert areas. Is it to stay away from snakes and such?

 

easier to open/pack up

 

I have a truck tent, there are some real advantages. Such as:

Always having a NOT MUDDY place to pitch it
It will never blow away
Very easy to set up

I use it when i go riding in the desert or mountains. Its very handy. They are more money though and you can only fit two people in it. My Tacoma has a shell so its sitting in the garage right now.