How useful would your toolbox be to you if all the tools were the same size and shape and did the same things. It might work wonderfully sometimes and frustrate you in others.
I'm a cop, I work with people from a variety of backgrounds who also happen to be cops. The situation is similar to my dojo, except there we are all akidoka.
In a cop situation where someone is getting the snot beat out of them, I REALLY like it when alot of big, burly, grumpy guys show up. However, if the situation is merely begining to spin out of control and I am trying to maintain order, I REALLY like female Officers. They don't have a lot of weight to toss around, they use their heads before they need to use their hands. And if things go bad, a baton strike (koshi?) delivered by a 120 pound female is not any softer than one by a 210 pound male.
In dojo situations women can also great to practise with. I have to go lower to get under their centers. I have to do my technique more precisely to avoid "muscling" them. When I take ukemi for them I have to be mindful of nimble women or I will hit the mat instead of meeting it.