As for the imperialist thing, they try to hammer down their thoughts more than often and since Science has provided big tools to establish claims, they have left the old age philosophic discussions over morality, reason, free will, predestiny and the whole religious baggage. Although the message becomes far more understandable to the avreage man, it becomes kind of hollow and this makes many people feel that something has been left behind. Read Russell and then read Harris. Yes, Russell was a philosopher but Harris' works are downright accusatory and more than often targeting one group only (as he clearly has apologetic tones towards Judaism). Similarly, even Dennett who is a philosopher does not come as big a package as Russell. Imagine Bertrand Russell armed with today's evidence on evolution. He would destroy all competing debates. The imperialist thing is that more than often they show sympathies with the "liberal religious groups" i.e. the sunday church people. I find that offensive for belief in all tis forms, moderate, liberal or fanatic has equal value.