Stinks, yes, but it's not unexpected.
The only new system for home theaters with backwards compatibility is the Wii U. It's because the Wii has reached market saturation and is expected to cease production stateside in 2014. The purchase of new Wii's has dropped off significantly, the resale cost of a used Wii at resale locations has bottomed out, and so Nintendo has made the decision to discontinue the manufacturing of the console in favor of the Wii U, most likely by this spring the announcement (which has already been hinted at coming from Nintendo) will be made and by summer we will no longer see new Wii's.
Xbox 360 and PS3, however, still dominate console sales, even in this holiday season. They're still in-demand and, despite the fact the new consoles are out, developers will be treating them as the primary gaming consoles for which they should be developing software for. Because they're still so in-demand, if the were to make the new units backwards compatible, they'd essentially kill any point in somebody buying a PS3 or 360. Considering there's still 6-14 months where they're going to still be the primary consoles of the majority of gamers, they're not going to add a feature to the new consoles that would deaden the sales of the existing, still highly active, consoles. So as a result, no software, no downloads, no content can be accessed from the Xbox One/PS4 that was accessible on the previous editions of the console.
That said, most gamers and industry folks agree that when the new consoles become more the standard and there's value in discontinuing the old models, you will see that the next versions of these consoles will be backwards compatible. Which is why, my friends, buying a console at launch can be a risky business. Yes, you get it first, but in 18 months they announce that the new versions of the One and PS4 are coming and they'll be smaller, have bigger hard drives, be less buggy, and will be backwards compatible to the 360 and PS3, all for about $100 less than you paid for the one you got at launch, you'll either want to buy it again, or you'll have to enjoy your early buy with less features while the second version of the console becomes the version that most gamers buy.
Then again, you wait long enough, nobody will care if it's backwards compatible anyway because the content for the new consoles will outshine the content for the old. Like everybody was so excited 360 and PS3 were backwards compatible for like the first year they were out, now who even notices, cares, or uses that feature? I can't remember the last time I played an Xbox original on my 360 or a PS2 game on my PS3. The good stuff they'll "remaster" and make an "HD remake" of, release it as a gold edition, and you'll buy it all over again. Like Windwaker. I have it already, I have the console that plays it, and I have a Wii which was backwards compatible to the Cube. I could have played it anytime I wanted. But they re-did it, gave it HD graphics, and despite the fact I had it and could play it on Wii whenever I wanted, I got it day 1 for the Wii U. Game makers and the console folks know this, so they know people will care until the next Halo or GTA comes out for the new consoles, then suddenly nobody will remember or care it wasn't backwards compatible and will buy it anyway.
The only real reason it's an irritation now is because neither console has any really great, distinguishing games for it.