Strange how the mk2 became so iconic when it is only a mk1 with 23 % increase in resolution ( which 90% of users didn't need ) and video ( which 90% of users didn't need ). When we got our first mk2 at Building Panos we thought the video was amazing, but very quickly found a proper video camera was much better for any casual video that we wanted. The video function on the mk2's hasn't been used for years in our case.
Obviously it's a very capable camera for many applications, but then so was the Mk 1.
The mk3 deserves to achieve this iconic status because it broad range of capabilities is truly impressive
ISO and IQ are a lot better than mark I. The cheap video capability is also a big plus. Maybe for your case you don't find 5D2 video great but here in Asia, 5D2 video capability is pretty much used especially by wedding photographers, videographers because it is less expensive than videocams and serve a dual purpose. True, they also use a video camera but it is too expensive to have multiple videocam. The best course is to have one main videocam and have several 5D2 to cover multiple perspectives. Even until now, they are still used pretty much by a lot of wedding and event photographers.