I think the big difference is a the the iPod offered users a superior UI, a simple syncing experience, was vastly smaller, and weighed a ton less. What does the OnHub offer?
It offers a simplified setup - something you do extremely rarely. That's a lot different from a UI that you use every single day, a size and weight that change it from something non-pocketable to something easy to pocket, or a syncing interface that you might use weekly. Google is solving something that is annoying, but done so infrequently that it might not matter.
The iPod made music easy and portable which the nomad didn't. The OnHub has a cool setup process that I'll run once every 3 years?
It does have great specs, but the question is whether they help me. Seems like they don't help speed. AC1750 routers are more than enough for my 110mbps internet and can be had for less than half the price. Why not put a microphone and chromecast in it and make it a voice capable casting device? It has a dual core 1.4GHz arm processor with 4G of storage and a gig of ram.
The thing is that it solves something that is crappy, but that you almost never have to deal with and doesn't seem to offer a lot on other fronts. As someone doing the Boston apartment shuffle today, that's a crappy experience and I've done that more often than I've set up a router over the same period.
My hope is that it might push users away from the $40 routers to $100 ones. Google could price anchor people toward more expensive routers and that's good for Google with more reliable, fast connections. Google might also add more OnHub features in the future that might make it a lot more attractive, but I just don't see it solving ongoing pain points in the way that the iPod did. It solves something as rare as moving and just like I hired people to schlep my stuff, people can buy a router and give the neighborhood techie kid $20 to get it going.