No one's asking anyone to cross-compile binaries for every OS. You compile binaries for the few important platforms and provide source for the rest. As I mentioned in my other reply, open source projects have been doing this for a long while.
Almost every open source library on my Mac is compiled from source. Name your system: homebrew, ports, fink, they have all switch to compiling from source.
Every scripting extension repository I know assumes you have a compiler to compile native libraries for extensions.
And this has been true for "a long while". The change you are proposing is not trivial, and it has far-reaching implications. It is a step backwards, and one that every developer should oppose.
