The real issue here is, we simply do not know how we will be attacked. Anytime someone says, "Well, I just hope I'll be able to chamber a round before I need to fire," they're making an assumption as to what their particular situation will be. But, the same goes for the people who say that you won't have the ability to chamber a round before you need to fire. That's as much an assumption as the first statement.
If I wanted to make sure I was covered in any circumstance, I'd sling an AK over my shoulder and carry it everywhere. But that's not practical, so I make a compromise and carry a much smaller, less effective handgun. I make compromises when I carry that too. In an effort to aid in concealment and retention, I use a holster that takes a little bit of extra time to draw from than say an open top OWB holster. I'd love to carry two spare magazines, but I usually don't because I don't have a good, comfortable method of carrying two spares that are in a location that's available immediately, and in a place where they won't move around. So I compromise by carrying one spare.
Carrying a weapon is all about compromises. We compromise on weapon, clothing, holster, ammunition, just about everything. For me, the compromise of a little potential additional safety, by losing some ability to fight is simply not one I can make. You may decide the compromise is worth it. Just because your situation and comfort level allow you to carry Condition 1 does not mean that someone else's decision to carry Condition 3 is wrong. It's right for them. I personally would never recommend it, except in certain, very specific circumstances. However, if we're ever at the range together, and you tell me you carry Condition 3, I'll probably talk it over with you, and at least find out why you do. My father in law carries his 1911 Condition 3, and we have the conversation just about every month. But he's not comfortable with having a round in the chamber, under a raised hammer, and he understands what that means in certain circumstances, and he's accepted that.
Bottom line: I would recommend everyone consider carrying Condition 1. But if you are not comfortable, or for whatever reason you decide that you simply can't carry Condition 1, then don't!
Also, someone mentioned carrying a gun in Condition 2. I would only recommend this with a gun with a decocker, and in that case, (likely a DA/SA) it would really be considered Condition 1 (since a trigger press will fire a round, without manually cocking the hammer). If you've been doing this with a 1911, I really hope you've never had an ND...and I hope you never have one in the future. Lowering a hammer by thumbing it down and pulling the trigger on a live round is incredibly dangerous.