Jayjay : there's a conflict of requirements between designing desktop/console games that "need [the] extra content and CPU" and targeting the "dual-core CPU with HD4000". By essence applications made to run on low-spec hardware should be stripped to the bare minimum, without the extra content and cpu-intensive stuff, to ensure it runs well.
Btw, have you profiled your game to see why it performs badly on some hardware ? Maybe it's just a bottleneck that can be avoided or worked around
Some very good showcases are progressively appearing ; I'm thinking The Next Peneloppe by 
Aurel, CopyGirl and the Metroidvania Gamekit by 
Tokinsom & 
7Soul, etc. This proves moderately complex games can be made to perform well.
Native and platform specific optimisations are always done last on a game project, and they don't account for that much in terms of performance boost. Optimising the content and reworking the algorithms usually do most of the job.
Additionally, depending on the hardware, well designed content, good logic and native tech sometimes aren't even enough. For example a specific generation of mobile devices was absolutely terrible at processing certain types of graphics things (few and poor pixel processing units, abysmal texture read operations, appalling blending performance, etc.) ; to work on these devices, entire sets of art assets needed to be reworked to avoid this hardware limitation ; basically spreading the cpu/gpu/ram/vram load differently. Just an example, but typically this is an extreme case of something a tool cannot do.
It's impossible to create complex games easily ; the complexity of the underlying technology always reflects the complexity of the games. Which also means a stronger constraint on the user to understand the technology in order to use it efficiently.
Ease of use, functionalities, efficiency, portability, cost, etc. One single solution cannot do it all, because these are conflicting requirements.
There are already lots of other solutions to create games - native programming frameworks, portable engines, visual tools, complex modular editors, etc. C2 fits nicely between all these and provides a good answer to a collection of problems.