Seriously, the AppleTV is only a 'failure' by the standards of the iPhone and iPad -- most companies would love to have a product that sells nearly 3 million units per year! The margins may be lower than the iPad's, but my understanding is that it does still make a decent profit.
Thunderbolt is an Intel technology and an incredibly useful one. The available products are already starting to look impressive in functionality and prices will come down before too long; Apple themselves use it to provide gigabit ethernet on devices that are about the same thickness as an RJ45 connector, and they sell those for just $29.
I think you've picked a terrible example. I had to buy this very adapter yesterday, and I slowly start to wonder if I should've bought the USB one instead. It looks almost the same and doesn't prevent me from connecting an external DVI screen like the Thunderbolt adapter does. Maybe there's a Y-piece, but it'll certainly be another $29 or more.
I'm not fully convinced that there's much advantage to the USB one over just using wifi, except where the latter is unavailable.
And even if the USB adapter is dog-slow, it's all I'd need onsite with clients (email, Skype chat). I'm still not sure if I made the right choice in the long term :/
Lisa - was the precursor to the Mac. It was beta but everything you see in a Mac was in Lisa.
AppleTV - STBs are really, really hard. I think this is the last gasp for TV. AppleTV just makes it useful again when the world is moving to watching things on a laptop/tablet.
Thunderbolt - fantastic piece of tech probably has longer legs than eSata, which it is supposed to replace.