1. What exactly is special about each of them ? 

2. Updates ARE obstacles and that goes especially for the HARDWARE modifications. Newer models of the devices try to have as much security as possible to prevent old hacks from working. Going by trends, both the HD twins likely suffer more from piracy than the WII did especially the PS3 and not to mention those traditional gaming crowds are more likely to be exposed on the knowledge of console hacking than the new blood that Nintendo obtained with the WII ... 

3. The high price can be attributed to Gamestop's pricing. Demand does not suddenly disappear if one is interested in a product and Xenoblade Chronicle's sales show that demand has been mostly met before 2013 going by the sales numbers ... 

1. Luck mostly.

2. Wii updates are optional, you just opt not to do them, like I did with my modded Wii. The homebrew scene on Wii was huge; I know because I was a part of it. 

3. It was a limited run, this is common knowledge. Even outside Gamestop it was expensive as hell for ages. Only recently has it deflated somewhat.

Wii U has a higher attach rate, a lot of people already have the Wii game. Not as many people have the New 3DS. Simple. XCX > XC 3D > XC

X has to come on top, it has way more potential than the original and even the port. Hopefully Nintendo won't screw it (They made Shulk amiibo exclusive to Gamestop... WHY?), otherwise sales will be much lower.

I wish nothing but success to the franchise and Monolith, but hopefully the N3DS port won't do amazing numbers... It's like Xenosaga I&II on the DS... Those games make no sense on a handheld, high sales would just motivate them to release more watered down games.

1. That would be like saying luck gave Nintendo two jackpots (DS & WII) in a row. There's a clear reason for why everything is the way it is and luck doesn't explain anything ...

2. The SOFTWARE updates are optional however the HARDWARE ones aren't. The homebrew scene on the WII is relatively small in comparison to the rest so Xenoblade isn't the only one at a disadvantage and the only platform that I can remember at the time where console piracy was truly rampant on was the PSP. The WII had the benefit of a newer audience who were less educated about these topics so they were less likely to attempt such actions. 

3. Yet most of the sales happened on it's first year in NA ... 

1. Every rule has a few exceptions. Doesn't change that new IPs generally sell less than established brands. Fo every new IP takes off, there are several that don't.

2. Hardware updates never proved any obstacle when I got my second Wii modded in 2012. And don't make the mistake of assuming Wii owers are all casuals; there's tons of homebrew and hacks available for it, custom patches, region code circumvention, emulators, homebrew games...

3. NA is still the biggest gaming market.

1. Those are not franchises yet but how did Heavy Rain, Alan Wake, Dark Souls, Darksiders, and The Last of US succeed despite been new IPs ? Xenoblade wasn't the only one that had to prove itself but many others did as well ... 

2. I don't hardly even use the term "casual" since the idea behind it is silly. I merely hinted that they were less "educated" on console hacking and online trends show for it ... 

3. It is but it doesn't change that the vast majority of it's sales came from it's first year in NA ...

1. For every new IP that is a success, there are many that don't make it.

2. There were still enough tech-heads for there to be a quite a bit of homebrew content available though. Wii modding was not rare, or difficult. Nintendo didn't exactly make it hard to break into.

3. It was still a limited release though.

Yes but Xenoblade wasn't the only one to face those challenges ... 

True. All franchises must at one point overcome the challenge of being a newcomer. Being an unknown JRPG exclusive to the Wii late in its life was a bit tougher than most have it though.