I don't know a lot about erlang but i doubt it makes parallelism easy all of the time. I'm sure there are many cases when the default actor model works great, but that's not a reasonable model for _every_ problem. Shared memory multithreading (for all of its faults) can be very effective for certain kinds of problems. So it can be worth the difficulty.

Writing parallel code is easy only when compared to writing Erlang (or similar) code ;-)