Not talking about those who are depressed and just want to end it...
I think that it is the natural outcome of growing and maturing in Christ, understanding His heart and seeing and living in this fallen world to just want it to end and be there with Him.
It is like the closer our relationship is the more "homesick" we become. I go through the same thing very often. I know that it's not time because I'm still here, but it wouldn't bother me a bit if it ended right now.
We are finite creatures in the age of technology standing in front of the microwave oven screaming, "HURRY UP!"
To God being infinite, we are already there with Him.
I agree 150%! But, for me, it goes beyond being homesick. It hurts me to see the condition of mankind around the world. It's so bad, and getting worse all of the time. Humans have such a great capacity to love, but they have an equal capacity to hate and be incredibly cruel to eachother.
I can't even imagine how much this hurts God. It's not even something that I can comprehend, and I wonder how much worse it's going to get before He finally comes and ends it all.