Luckily all the new consoles use x86_64 processors for their main processors, so no low level emulation will be required.
Since there are very few exclusives, there's little demand for it to be emulated in the first place. And from what I understand, the XBox isn't fondly-remembered by geeks. The XBox was the console of choice for people who liked to make fun of geeks and nerds, and as such most people who have the skills and the desire to write emulators (i.e. geeks and nerds) have a pretty strong aversion to the XBox. That the most popular games for the XBox weren't the kind of games that were enjoyed by nerds doesn't help, either. There's very little overlap between emulator programmers and people who care about the original Halo or old Madden games.
This 33c3 talk gives a lot of fascinating information on how PS4 differs from your run-of-the-mill PC and what kind of issues they hit when trying to run Linux on it: https://www.youtube.com/watch?v=QMiubC6LdTA
The PS4P increases everything except the CPU cores count: CPU clock to 2.1GHz, compute units to 36 (hence 2304 cores) and GCN frequency to 911MHz.
Technology aside, it's also a matter of interest. Many XboxOne and PS4 games already have PC ports, so there is less need and interest to create emulators. Nintendo consoles on the other side have many exclusives, so interest in emulating them seems to be higher.
Only time will tell.
Probably a matter of demand, too, since it's got very few decent games that aren't 1) available on another console, or 2) available as an (often superior) PC port