I think there still is some truth to @dxm_dxm’s words. True, Dalai Lama has millions of followers worldwide, but their numbers are much smaller than those of the Theravda Buddhists whose existence most Westerners are not even aware of and are completely negligible if you compare them to the mainstream Chinese and Japanese Mahayana. For some reasons, and I assume that they are at least partly of political nature, Dalai Lama was given an immense media exposure and is perceived by many, if not most non-Buddhist people in the West as the speaker for all Buddhist traditions, some kind of a Buddhist Pope, if you will. When I say I am Buddhist, people automatically assume Dalai Lama is hugely important for me. In my discussions with Non-Buddhists about the alleged violent nature of Buddhism or evil committed in the name of the Buddhist religion the Tibetan slavery is an argument that comes up almost inevitably and it takes me a huge amount of effort to explain to these people that accusing a Theravidin of Tibetan slavery is something like accusing a Lutheran Christian of the Crusades. Not that the Theravda was never used for unethical or evil purposes, but it is still a nuisance when your religious tradition is accused of something it has absolutely no connection with.
If you want to assess how influential a figure he is in the eyes of the Western world, you may just come into a random bookstore and look for all the books having to do with the Buddhism. At least 40% of them will have some connection with Dalai Lama or Tibetan Buddhism. With all due respect to the Tibetan traditions, this is a highly odd situation. Just imagine that 40 % of all book on Chrtistianity, sold in Asia, would be about Evangelical U.S. Christians, that people would have no idea the Orthodox Christians even exist, think that the President of the LDS Church represents the entire Christian tradition and reproach Catholic Christians of the Meadows Creek murder. Of course, this is at least partly not Dalai Lama’s fault, and I value his humanitarian effort and his popularization of the Buddhism in the West very highly. Some of this would be hardly compatible with the modus vivendi of the traditional Theravada or Early Buddhist Sangha, but we should still give him credit where credit is due.
At the same time, for me Dalai Lama is not a religious authority. I don’t listen to his talks, I don’t think he is a Bodhisattva or an accomplished meditation master or that he has attained anything worthy of mention on the Noble Eightfold Path. I could listen to his talks, but what for if I think there are much more accomplished people I can learn from? I bet not many Tibetan Buddhists are keen on reading Ajahn Chah’s Dhamma talks, he’s just irrelevant to them 
Dalai Lama can position himself as an ecumenical Buddhist leader, but for me he is not a religiously relevant figure at all. It is not even really necessary for me personally to build bridges to the Tibetan Buddhists: I fell like they are Buddhists just like me, and they can be monks or nuns, and I respect them and their opinons and will support them with resources like food, accommodation, or money if I can. It’s just that I think a pretty good chunk of their teachings is completely wrong. Why should I build bridges to them, then? It is just as if I tried to build bridges to my non-Buddhist fiancée or my Muslim neighbour, a very nice Tunisian guy, where no bridges are really necessary, we are getting along quite nicely.
To sum it all up, Dalai Lama is for me a medially over-exposed Buddhist who has to take part in an absurd situation where he is represented as a spokesman for the entire religion. He is an ethically admirable person worthy of respect and support, his initiatives are also very praiseworthy. Some of his opinions and statements are controversial, but so are those of Ajahn Brahm, it’s normal. That is pretty much it, there’s no big difference between Dalai Lama or any other ethically accomplished Buddhist.
I mean… Does the monastic Southern Buddhism have to be brought together with science? Sure, as a layperson you can do whatever you will and maybe, just maybe there is a lack of scientific intitiatives among the Southern Buddhists, but I always thought that as a monastic person you have other priorities than bringing together the Dhamma and science. Besides, textual criticism and amazing translation work of Ven. Bodhi, Ven. Sujato, Ven. Brahmali or Ven. Analayo and many other venerable bhikkhus ans bhikkhunis, much of it having to do with pretty abstract and theoretical issues of hermeneutical nature, or distinct interest in the reincarnation research among certain Souther Buddhist circles: this is all science. It’s not even bringing together of the Dhamma and science, it is science, pure and simple.
