[citation][nom]Madjimms[/nom]Why doesn't ARM just buy AMD & combine its technology WITH AMD's?[/citation]
ARM has no use for the x86 instruction set and low-power mobile/SoC processors do not need any of the power-hungry and logic/register-intensive single-threaded IPC optimizations common in mainstream x86 desktop CPUs either.
The reason ARM CPUs have relatively primitive architecture with few fancy tricks is not lack of know-how since many of those tricks are very well documented/researched and so old that many of their patents have expired years ago. It is because those simply do not fit in ARM's transistor and power budget for their core market.
If you look at the server/HPC market, CPU vendors are shifting from complex general-purpose CPUs optimized for single-threaded performance towards higher densities of "dumber" CPU cores and GPGPU/Phi to favor thread-level parallelism instead. In a well-threaded environment, you gain a lot more potential performance per Watt from investing transistors into execution units/threads/cores than investing them into 'tricks' to improve single-thread performance.
What CPU manufacturers can afford to put in their CPUs depends on how they choose to compromise between single-threaded performance, multi-threaded performance, power and transistor count.
For desktop CPUs, the most important factor is single-threaded performance. For servers/HPC, it usually is multi-threaded performance. For mobile/SoC, it usually is power and die size. Three different markets, three different and largely mutually exclusive priorities.