To what extent does the Buddhist dharma present in the west as a critique of modernity?
I think you need to be more specific with your terms.
There is a lot of Buddhist dharma present in western countries.
Some of it was quite successfully transplanted from Asia with minimal modification. However, those forms are often referred to as "ethnic Buddhism" and not normally available or popular with the natives.
On the other hand there are plenty of heavily modified traditions that a lot of people in Asia would not recognize as Buddhism. For example titles such as this would not be recognized as Buddhism in Taiwan:
Even in the transplanted organizations and traditions in western countries such things would not be recognized as legitimate. Rather, I imagine most would consider such works as misguided, immature and distasteful. However, a lot of younger people in the English speaking world at least find such works appealing.
Zen priest Brad Warner asserts that Buddhists are encouraged to jack off. Meanwhile the late Chan master Venerable Master Shengyan has written that masturbation is inappropriate.
Brad Warner would represent the typical values of a younger American generation. Anything he has to say would probably conform to the standards and values of present day American youth. Venerable Shengyan's words would be prone to be regarded as old fashioned, traditional and archaic, but then not many of his works are translated into English yet. I don't think they would sell well on Amazon either.
So, I would say the trendy forms of Zen in America are probably entirely compatible with modernity. However, more orthodox Asian traditions, with the exception of Japanese Buddhism at present, would come into conflict with many modern values and ideas.
Again, going back to Venerable Shengyan, in one of his Chinese works he points out the scriptural support that states when one takes refuge in the Triple Gem one comes under the protection of a number of guardian deities. If asked for scientific evidence of the existence of such deities I imagine he could not provide anything. However, in the Chinese speaking world science and Buddhism are generally not taken together. You would not walk into a temple and ask for physical proof of the existence of Guanyin.
On the other hand, in Europe or North America there is a continuing trend of demanding scientific proof for religious claims.
Now, American Zen, as far as I know, would never postulate the actual existence of Kannon (Guanyin) and guardian deities even though historically Japanese Zen actually did. However, American Zen conforms to the standards and values of the modern world as it is understood in Euro-American terms.
Again, Chinese Buddhism would not, but then they are not actively challenged by the scientific community.
Keep in mind Chinese Buddhism is in the west, but it is largely ignored by the natives. This is kind of ironic considering Chinese Buddhist organizations are probably the most wealthy and well organized.
1/ Buddhism as a negation (escape from/critique of) the forms of instrumental rationality which (according to sociologists such as Weber) modernity demands of its subjects. Inclusive of this is a negation or critique of the ethics of utility and the individualism it presupposes.
I think my analysis above relates to this. American Zen makes no demands contrary to the demands of modernity. In fact it tends to discourage people from taking the orthodox ideas and traditions seriously.
Tibetan Buddhism in North America and Europe is different, but then it is undergoing commodification. This indeed would be the influence of capitalism upon what was originally an isolated religion in Tibet and Mongolia. In other words, westernization.
In that sense Tibetan Buddhism is not reforming the natives, but the natives are reforming it to suit their values.
In all honesty I don't see many Buddhist thinkers, in the English speaking world at least, going against modernity. They tend to reinterpret Buddhist ideas to make them tasteful to modernity. Some toss in jargon from quantum physics in an attempt to validate their ideas. Others defer to accepted lineage masters of western psychology for validation of Buddhist ideas instead of the arguments and treatises of Buddhist masters.
I don't know why for the longest time people have deferred to Jung about Buddhist ideas. The modern intellectual needs validation from a thinker whose testimony is widely accepted.