Personally, I love the downward dog, plank, etc. for a simple reason: There are so many wrist and shoulder injuries that occur form these positions. Since I often work with people who are in their post rehab stages, it's great for business! So I really hope that yoga instructors keep teaching those postures! :D :p ;)
Now getting serious: The truth is, no one form of fitness is good for everyone. Unfortunately, people tend to gravitate towards whatever comes easiest to them. As a result, you see more men in the weight room, and the women all flock to yoga class. In many cases, it should be the other way around.
BUT.... Nothing is ever that simple. Some women have more male hormones than others. You can tell by the body type: small hips, small breasts and not too many curves. Body fat is pretty low and metabolism is high. These gals may have the same types of flexibility issues that guys have, so yoga is actually good for them.
But let's look at the other scenario: Take a woman who is somewhat curvy. Without aerobics, weight training and diet, she would probably be overweight. She is usually pretty loose jointed and she may have small, hyperextended wrists. Let's say she works all day at a computer, at a workstation that is less than optimal, ergonomically. Put her in a downward dog position, and it's curtains.
If she continues to do yoga exclusively, she will always have a weight problem, and her muscles will never be toned. Futhermore, if she keeps over stretching her hamstrings, she is messing around with a muscular imbalance between the hamstrings and quads. Put her on the slopes, and that's the express path to an ACL tear.
Pequenta, when you say you have tight hamstrings for a yogi, that may actually be a good thing. Most ski instructors will tell you that if you are skiing correctly, you will be feeling your hamstrings more than your quads.
Speaking of tight hamstrings, in some cases, even that is sometimes misdiagnosed. In some cases, the real issue is the hip flexors. Stay with me on this. If your hip flexors are tight, they will take over the work that the hamstrings are supposed to be doing. This trains the hamstrings to become progressively weaker, so in any task that they are designed to perform, they are going to hurt like crazy. In some cases, when people stretched their hip flexors, their hamstrings no longer felt so tight.
Back to the gender thing. If you read the thread on Epic about the 5 second stretch, you will notice that some guys said that they stopped getting injured after they stopped using stretch as a warmup. So even men, who usually need more flexibility than women, can get hurt by too much pre-skiing stretching.