This isn't really true. Women have been itching to do the same things as men since time began...look at the glass ceiling and how we desperately want to smash that thing! Not to mention Tomboys have been around forever, plenty of little girls prefer traditional boy toys to girls, and there are even cisgendered women who are more comfortable in male assigned clothing than women's - even buying jeans from the men's department! Not to mention the more fetish aspects that women can experience (I won't go into details for fear of annoying the powers that be, yet again), but cisgendered people cross gender boundaries all the time. I also think there is psychological fulfilment for women who cross traditionally male boundaries and I'm sure many also feel excitement. Hillary Clinton is probably just itching to get Obama's job off him!
The difference I see is cisgendered women can cross these lines without leaving their female identity behind. Crossdressers like Jennifer and my H also cross gender lines without leaving behind the male. But others cross the line and temporarily shed their usual gender identity in order to join the other side and that to me is TG.