Meaningless, meaningless

Here's one for the grammar pedants:

Why, when you're imagining something, are you supposed to say, "If I were..." and, "I wish I were..." rather than, "I wish I was..."?  I know that's what you're supposed to do because my mum told me, but why?  Come to think of it, why don't we say, "I wish I am..."?

Bloody stupid language, English.

The other thing I've been pondering is why, if, as is generally acknowledged, women who work together start to "coincide", why isn't the whole world on some great universal cycle where we are all grumpy at the same time and there is a peak in the number of babies born every month?  Answer me that, huh.