Backward incompatibility.
doc-brown
by Peter Brown on February 1, 2014
"There’s no doubt that Sony spoiled us when it made the PlayStation 2 backwards compatible with original PlayStation games. The convenience of being able to immediately tap into a giant library at launch was a hit with a lot of people. Though there was some legacy support to be found in every console over the course of the last generation, the PlayStation 3, Xbox 360 and Wii all had issues at some point; Sony and Nintendo eventually stopped including the required hardware in their consoles, and Microsoft relied on spotty software emulation that was abandoned by its developers well before it was “complete.” Still, backwards compatibility felt like the rule, rather than the exception, for a while.
Consequently, people were understandably surprised and disappointed that neither the PlayStation 4 nor Xbox One would ship with legacy support in tow, probably due to a lack of understanding that a shift in hardware architecture, which in turn affects how game code is interpreted by the console, is the main culprit. There are a lot of advantages to switching to a familiar, PC-like x86 CPU, especially for developers, but simple implementation of backwards compatibility is not one of them. This isn’t a total roadblock, however, as evidenced by Digital Foundry’s recent report that unveiled the existence of a PlayStation and PlayStation 2 software emulator currently in development for PlayStation 4..."
http://www.gamespot.com/articles/how.../1100-6417455/
I think this will help the PS4 a lot, and with this news I might get a PS4 instead of a Wii U.