I think this really comes down to a matter of perspective. Is the Buddhist view that most of our suffering comes from our own mental reactions really that revelatory? I dunno, I think it's something most people should be able to work out. That's not to say there are not deep philosophical traditions in Buddhism, there certainly are, but I think the reason that most people immediately think of them rather than the religious features is predominately down to the way Buddhism has been promoted in the West. If Christianity had been imported to the West when enlightenment values were highly regarded I suspect we would have a very different view of it.
The problem with using D.T. Suzuki as a source is that he is probably one of the clearest examples of someone who repackaged Buddhism to make it appealing to Western audiences. Reading his writings in Japanese on Zen make this distinction abundantly clear. This is not to say he invented things wholesale but it is fair to say that Suzuki is not an impartial source.
Depends on which Buddhism you are looking at and Zen Buddhism in Japan is just as institutionalised and ritualised as any number of other forms of Buddhism. It's not really God-centric but I would certainly say that it is ritual-centric and I also think you'd find a lot of woo amongst staunch Zen practitioners.
I would actually go so far as to say you could immerse yourself in almost every form of Buddhism promoted in the West, including Tibetan Buddhism, and still retain an atheist/skeptic perspective. The only problem with this, I feel, is if you then try to argue that the atheist/skeptic interpretation is actually what REAL ORIGINAL Buddhism is really all about.
BTW, if anyone is interested in the story of Buddhism being promoted to the West I recommend having a look at 'Curators of the Buddha' by Donald Lopez or any of the books dealing with the World Congress of Religions held in Chicago in 1893 (or for Tibetan Buddhism 'Prisoners of Shangri La' also by Lopez).