Because they don't need your business. Google is big enough to start something like this in the way that they mean to carry it on.
They're obviously aiming their structure at the >$100 a month/2 months worth of click-through sites.
As I have stated, it's impossible to know if this will work for you without knowing the fee scales. It may be a case of suck it and see.
But you're right, it's a waste of time for you if you have to wait 8 months for a cheque. That's the part I need to calculate and work out for myself also, but we can't do that within any reasonable guess without knowing what the PPC fee's are.
The problem with my site is to run Adsense I need to switch to a commercial server and it's impossible to tell if that's worthwhile or not.
Very tricky call.
What are your other affiliates like? Can anyone recommend something similar to Adsense, but where you know where you are financially?