A big reason I use (and enjoy using) python is because it doesn't feel like a "bolted on" solution. All current concurrency options for python feel bolted on to me personally.
The python internals weren't designed for this, which is the reason they have to use monkey patching. It doesn't mean that you can't make something work, but it means the language/interpreter sure aren't going to help you make it work.
I just couldn't write something which depends on speed and concurrency in python right now, knowing there are solutions much better designed for the problem. Python holds a special place in my heart, but unicode and concurrency aren't so good right now.
However, this future async support and unicode support in python 3 very much excites me!