Together They Fight Crime

I recently caught a bit of Elementary. I must say I'm enjoying it a lot more than I thought I would. I got me thinking about a subject that's been puzzling me recently, so I figured I'd go ahead and rant about it a little. To illustrate my question, let me give a brief summary of some of the shows I see on TV these days:

The Mentalist:
A female law-enforcement professional solves cases alongside a male non-law-enforcement specialist.

Alcatraz:
A female law-enforcement professional solves cases alongside a male non-law-enforcement specialist.

Perception:
A female law-enforcement professional solves cases alongside a male non-law-enforcement specialist.

Castle:
A female law-enforcement professional solves cases alongside a male non-law-enforcement... guy.

Fringe:
Two female law-enforcement professionals solve cases alongside two male non-law-enforcement specialists.

Psych:
A female law-enforcement professional and her partner solves cases alongside a male non-law-enforcement specialist and his partner (OK, this one doesn't quite sound the same on paper, but it has some of the same dynamics).


OK, some over-simplification there, but there's definitely a running theme. And I can think of more shows with a similar theme or balance, even if the relationship isn't the same on paper: Elementary, Life, Monk; they all have a male lead running around solving cases in unusual ways, while his female counterpart gets dragged along to support/balance/offset/keep him grounded.

Why is this? Is it something to do with a desire for a strong female lead, but not wanting just another cop show? By having the man not be cop, he can be "quirky" and "unpredictable", and perhaps even be the "awesome hero" by doing things better than the cops? Fair enough, but why is it always the woman who's a cop and the guy who isn't? Is it just easier to imagine a guy risking his life to fight crime on a regular basis even though it isn't his job, while if a woman does it we don't buy it? Is it something to do with wanting the guy to be the brains and the woman to be the muscle for a change? Or simply some form of "everyman" fantasy fulfilment spin on the detective genre?

I dunno. Just saying is all.