These are a very good solution. I actually think they are better solution that compromising the design of the iMac with more ports. I can run a single Thunderbolt cable to this dock and place it out of sight on the shelf under my desk, and connect the peripherals there. Or I can place it on my desk somewhere where its convenient to get to the ports if that's what I need.
All of it is better than having the ports on the back of the Mac, and the Mac having to be different because of it.