To understand women and attraction, an important thing that needs to be understood is that they use the word "attractive" in multiple ways, whereas when men say a woman is attractive, we almost universally mean "sexually" attractive (I believe this confusion has caused alot of misunderstandings in discussions of this nature). When it comes to understanding what women are attracted to, you need to look at what women - from an evolutionary standpoint - need from men The first is genetic material (See Genghis Khan's thoughts on pulling out). The second, manifests itself in many ways, but I'll use the umbrella descriptor of "physical/material security". The former of these needs is what drives "sexual" attraction, and the latter drives "relationship" attraction.
From the standpoint of purely sexual attraction, they like men who demonstrate masculine physicality and health. Masculine physicality can be expressed in two ways: 1) A man's capacity for physical work, and 2) a man's capacity for violence, and these two capacities overlap quite a bit (I'll give the psychological advantage to the violence camp though). Therefore, if a man's physical presence if found intimidating, you can rest assured that she finds you sexually attractive to some extent (by and large, bigger is better, up to a point).
When it comes to "relationship" attraction, this really just boils down to a guy being someone that will "stick around", ensuring her offspring and the offspring of her childern. This includes physical protection to a degree (pregnant women don't jiu-jitsu very well), as well as material protection (providing food, building shelter, etc).
Now, getting back to the figther/tough guy archetype; in short, women will find him sexually attractive, ALWAYS, at any age, what changes is the importance of sex vs. long-term commitment as a woman ages. When you think about this, it makes sense, as a woman gets older, her ability to compete with younger women diminishes. On top of that, an older woman is more likely to have children than a younger woman, whom will require parental investment. So when you hear a woman say that she use to be attracted to a type of guy and that her tastes have changed, what she really means is that her priorities have changed.
If girls you are meeting are saying that they aren't interested in a guy that they find physically intimidating, they're probably in "relationship hunting mode" and don't want to be smashed-and-dashed (instinctively, at any age, women fear this to an extent). An important detail to keep in mind with regard to the modern dating scene is that there are many women on "the pill", which causes her body to think they're pregnant. Therefore, the ones on the pill are more likely to seek out the "provider" type guy vs. the tough guy archetype. A quick google search will allow you to see many stories where a woman's attraction to her husband completely changed once she got off the pill when they were trying to start a family.
Long-winded response I know, just wanted to contribute. Hope this helped.