Originally posted by janneman by the way what is bad about big focus points?
To use a real world example. Let's look at the K-5 with its golf ball sized center AF point. When shooting a concert where you are shooting 85mm at F/2 to keep ISO down and shutter speed up you have a very thing DoF and focus becomes pretty critical. The lighting is awful. You are holding the little red square right over the singers left eye and firing away. Through the little bitty OVF of the K-5 you can't really judge critical focus under this light. When you go to chimp a few images you see that the AF has been grabbing the microphone (much higher contrast) in most of the images. Yow now have a nice collection of microphone pictures with some fuzzy guy. To compensate you have to use AF micro adjust to make the lens back focus and lock on to the singers ear.
On APS-C DoF is too narrow to get reliable AF, so I can only imagine how much fun the 6D will be in that situation. The K-5 needs 2x as many AF points that are 1/2 the size of the current points.
For people using slow glass or shooting wide angle the current size of the AF points is not an issue. For people with fast glass who shoot wide open, the AF points are way too big. I would be willing to bet this is why Pentax has not released any long fast glass in years. They know the AF can't handle it. For Canon, I doubt the people who can only afford the 6D are going to be buying a 200L or 85L as they both cost more than the body. The first Canon wedding photog who upgrades to an 85L to shoot at F/1.2 is going to be all over the Canon forums talking about how they got a defective 85L that can't focus consistently below F/2.8. The first thing I did when I got my 85L was set out to master F/1.2 photography with my 5D. It can be very frustrating. Like getting a MP-E 65mm Macro Lens as your first macro lens.