I don't really see going vegetarian as progress if you never go vegan. If the whole world stopped at not eating meat...dairy consumption would skyrocket and really things would most likely get even worse. If the person is using it as a stepping stone thats fine...if not they can just eat meat again...its no worse. I'd much rather be a cow destined for the meat industry...once they're full grown they're killed...diary cows get to suffer as long as the industry can keep them alive...then they get to be slaughtered anyway. I'd much rather suffer for 2-3 years rather than suffer for 10years.
The assumption is that if the world suddenly stopped eating meat then the increase for dairy would also increase. This is not likely but if most of the world over time became vegetarian i am sure enough of them would do it for ethical reasons and the production and consumption of dairy products could potentially stay the same and go down. The idea is that we just do not know. No amount of data can tell us this because it is so far off. I can understand your argument based on suffering but at the juncture we cannot know how the future of the dairy industry will act in accordance with the decreased consumption of meat.
I think that any figure that has the power to speak says in an article that the way that animals are treated on a factory farm grossed them out or disturbed them is a great thing. Think about the wave of conscious hiphop that spread in the early 90s that can be directly attributed to a generations vegetarianism or veganism.
The thing for me is the advocation of conscious consumerism. I was a vegetarian for a month before i was a vegan and it was identifying with animals first and then their by products that allowed me to become vegan. As usual we argue the point of view of what we are most familiar with and for me this process is what made me who i am today.