Well, I can only say, as someone who has both an Intellivision II and ColecoVision, that I'm very excited about these flashbacks -the controllers being part of the reason. The Flashback 2, as you may recall, has wired controllers that were compatible with original Atari hardware, and were quite excellent apart from the benefit of not being 30+ years old. From what I hear, the controllers on the Intellivision Flashback are also detachable -which means, in all probability, you can use the detachable controllers from the Intellivison II on the Flashback, and much more appealingly, the Flashback controllers on the Intellivision II. I presume this may be the case with the ColecoVision as well. Having completely new controllers that can be used on the original console hardware almost makes these Flashback devices worth the price all on their own.
Yes, those controller styles were far from ideal, but they are so part and parcel of the experience of these machines that it would have been disappointing if they didn't try and replicate them. Having modern microswitches would be a great improvement to them all on its own even without messing with the basic design.
I'm really surprised and delighted by the inclusion of those arcade ports on the Coleco. Given how much of the Coleco library is filled with arcade ports, it probably wouldn't have been worth doing without those arcade titles included on the Flashback.
As with the Atari Flashback, part of the reason these Flashback's are appealing is that the built in composite video is cleaner than what I've been able to get with video mods on the original system (this is most especially the case with the Intellivision, which simply does not mod well to composite video).