What's so hard about thinking up a new idea? Are Chinese people genetically incapable of innovation? Why is thinking up a new design for a manned aircraft so different from say a new ballistic missile, a new UCAV(have you seen their innovative designs?), or heck, even an Olympic opening show? Sure they take different technical backgrounds, but the ability to be creative is the same, no?
The reason Chinese engineers haven't gone beyond making advanced copies is because they have lacked the ability to manufacture anything more advanced. What's the point of designing an aerial vehicle which makes use of anti-gravity engines and anti-matter cannons when you lack the technical know-how to manufacture such things? And really, that's what it's all about. that's why I laugh at people who think "copying" an aircraft is so easy. For example, re: J-11B, if China can produce its own engines, radars, FCS, missiles, composite materials, etc. etc. do people REALLY think that it couldn't have come up with an original-looking airframe?