kernel patching elimination

Hi,

I've got a few questions regarding the design of Click router:
1) Why does Click do kernel patching (and fixing include files via
fixincludes.pl script) for g++ compiler instead of providing wrapper
functions, surrounded by "extern "C" "? Or even some abstraction layer
written in C?
2) Why doesn't Click use netfilter hooks for intercepting packets?
3) Why doesn't Click use NAPI for device polling?

Basically I am looking into possibilities to eliminate kernel patching
altogether and make it more independent/standalone.

Thank you,

Konstantin