OK. I want to emphatically note that I'm neither for nor against the release of the PS4K upgrade. The word I would use to describe my feelings towards it would be "ambivalence." I think it could be a neat option for people who want more horsepower. I think it could needlessly segment the audience. I also think it could wind up being a waste of time in that it might only receive token support and never realize its potential. I honestly don't know what to expect.
But having said that, I also don't think these comparisons are very apt. You're correct. You don't need to upgrade your TV every few years. But you also don't need to upgrade here. But if you actually do feel compelled to stay at the bleeding edge of tech, then you might need to upgrade your TV every couple of years. Whether it's due to TVs getting bigger or just more whizbang features getting added every year, or perhaps lower input lag, or better contrast, or... you get the point. I'm just saying that your TV from 4 years ago probably isn't the baddest thing on the block anymore in terms of deciding where this year's super bowl party is going to be. So if you're obsessed with keeping up with the Jonses, then yeah, you probably do need to replace that old set.
But if you're sitting there thinking "I don't care about the new features of the last several years; my old set is perfectly fine," then I think that mindset also applies here.
And I'm just going to close out by trying to reiterate that I'm not one of those FryShutUpAndTakeMyMoney.jpg people that is already sold on this device. If I had to put money on it, my suspicion is that the improvements from upgrading will probably be largely underwhelming. Of course, I might just be saying that as someone who has a pretty decent gaming PC. But I'm just saying that I'm not salivating over the possibility of 4K Uncharted 4. I'm not expecting a whole hell of a lot here.