I've spent a lot of time contemplating this very topic. Bugging out, to me, seems like a catch-22 as a means of survival - that is, unless you have it thoroughly planned out from start to finish. This means having an exact destination and the right amount of food, water, and other supplies to get there. I don't doubt the level of skill as an outdoors-man anyone here possesses. However, living in the wilderness for a long enough period of time would eventually take its toll on anyone. As was mentioned before, diseases from ticks and mosquitoes, weather, lack of food and clean water makes long-term survival untenable.
I guess the main point, for me, is that everyone's situation is totally different. I live in a small town, but the family farm is only about 15 miles away. Its a quick an easy drive, but if you end up hiking it, it could take a day or more(if you take the low road and stay out of sight). So, for me, an ideal bug out bag is enough tools and supplies to make it to the family farm on foot. The farm is more easily defended and better supplied than my house in town, so that's my obvious first choice for a bug out location. Now, if things got bad enough that I had to leave the family farm, I figure all is just about lost anyway. Without a bug out destination, you're just aimlessly wandering through the woods, and that really limits your chances for survival. That's why I think bugging out without a plan is an absolutely last option kind of thing. Furthermore, in a serious disaster situation, where communications are just about totally cut off, how do you get intel on where is safe and where danger is? That is, unless you just just pick a direction and see what happens.
Now it is totally possible that I have the wrong impression of what people consider bugging out. When I hear some people talk about it, I get the feeling that they think they'll be able to grab a pack and a rifle and go live off the land until the trouble blows over. To me, that's just a good way to run into one of those roving bands of marauders. Again, I may have the wrong impression of what people consider bugging out, but based on that I think bugging in is a far better option. This is a really interesting topic, so I do like to hear what others think.