Like with anything else, people will abuse the use of game cameras and utilize them in poor ways. However, people do that with anything that is designed to improve things (i.e. think about how people use cars today). Here are the benefits to game cameras that I have personally witnessed.

* It gets me more acquainted with the deer herd I'm hunting. Not only do I understand more about the bucks I'm hunting, but I also keep up with the does. This helps me do a better job of knowing how to manage the herd and predators (kill more/less does, start going after coyotes more, etc.). It also helps me keep up with the timing of the rut.
* It keeps me from shooting borderline bucks. I primarily "woods hunt", so when I have chances at big deer it usually happens in 5-10 second increments. With few moments to actually judge a deer, it helps if you've seen that deer prior to the encounter. When I hunt in an area, I usually will review pics from that area to remember what I'll shoot and what I'll pass - and it's greatly helped me.
* It helps me sit longer. The older I get, the more impatient I get on stand. Knowing a good deer is in an area keeps me in a stand longer - sat until 10:30 in a stand Saturday morning, something I'd NEVER have done in earlier years.
* It provides a means of bonding with other hunters. Some of my favorite interactions w/ folks I hunt with are conversations about trail cam pics. I sometimes get excited about a pic they share with me... and vice-versa. We also keep up with one another and tend to share more information with each other (which helps all of us be more successful and have enjoying hunts).
* It helps me understand if a leased property is worth keeping. With the amount of $$$ a person has to pay to lease property today, the LAST thing we want is to be pouring $$$ in a piece of property that doesn't have deer/turkey on it - or has a habituation problem like neighborhood dogs roaming the place. It also helps with detecting trespassers as well.
* It allows me to track the growth of bucks. I hunted an 8-point this year that ended up being broken up a week ago. I have pics of that particular buck for three years now - and the growth between years has been enjoyable to watch. This idea also helps me with the preceding point (is the place worth the $$$).
* It gets me involved in hunting year-round. In the past, when deer season was over, I'd abandon that place until turkey season... and then do the same until fall planting. Now, I am on the properties I hunt more often and I learn more - it's that simple.

I think a lot of the people who are against game cameras are guys who get to hunt a lot - retired people, those who have a lot of off time, etc. A lot of the things I mentioned up top here CAN be done IF you stay in the woods a lot. The issue for me is that I can't get into the woods that often because of work, family, etc. Again, I'm sure people use them in ways that are negative, but what innovation isn't going to see the same thing?