Eh, not letting the language ever evolve is a sure way to death, ymmv.

Forkserver is probably a better default, inheriting file handles, globals, and sockets leads to a bunch of subtle bugs - I'm not sure that's even a good feature, also ymmv.

And fork() is still available, so if it breaks things, the solution would be to explicitly ask for fork() - and I'd say for most casual uses of multiprocessing, a user won't know one way or the other which is what I meant by transparent.