I don't think you can generalise women when you ask this question but if we must talk generally then no, I don't believe all girls really want well-endowed guys. On the other hand, I also don't think most girls will kick a man out of bed if he happens to have a giant penis.
I think we've all heard it said that it's more what you can do with your penis than how big it is. There is no point having a 10-inch beast if you only have one speed setting and haven't mastered all the other bedroom tricks to impress a lady.
Also, anatomy is going to have a lot to do with how excited a woman is going to get at the prospect of accommodating a larger than average penis. Some women are built to enjoy them and others are not. For every Size Queen there is at least one woman out there who avoids anything over a certain length or width. As for all the other women in between, we'll assess how happy we are with Mr Big based on other factors, not just penis size.
It may be daunting for guys with average to below average sized penises to see what seems like a plethora of big boys on RedHotPie but it's important to keep in mind that women are after a variety of things in men, whether for play or more. The one thing you must never do is be obviously lacking in self confidence, especially if its rooted in your penis size. That is a far bigger turn off than the actual size of a penis.