Sorry Jon, but your Nexus One is almost 2.5 years old now. It's no longer last year's phone. And it just doesn't have the memory for the modern stuff.
You're still right that it's different from the old Linux tradition of keeping old systems alive for years and years and years, but smartphones are different in two major ways. First, they're advancing more rapidly than our desktops ever did, so even your (6-month-old) Galaxy Nexus is now being overshadowed by the Galaxy S III and HTC One X. Second, they're also not as upgradable. If you could add another 512MB of RAM to the phone, like you could with your old desktop machine, then you could probably run the latest Android on it.
Maybe in a year or two the phones will catch up to the desktops in memory, and then maybe they'll be able to have a longer lifetime. But of course all the vendors have an interest in making sure the phones go obsolete quickly, especially in the US where buying a new phone usually means being locked into another two-year contract.