Why reductionism about the self and other philosophical subjects is so common and so wrong

There's a new book called The Self Illusion by Bruce Hood. In an interview by Sam Harris, Hood explains his premise that the belief that you have a "self" is an illusion:

For me, an illusion is a subjective experience that is not what it seems. Illusions are experiences in the mind, but they are not out there in nature. Rather, they are events generated by the brain. Most of us have an experience of a self. I certainly have one, and I do not doubt that others do as well – an autonomous individual with a coherent identity and sense of free will. But that experience is an illusion – it does not exist independently of the person having the experience, and it is certainly not what it seems. That’s not to say that the illusion is pointless. Experiencing a self illusion may have tangible functional benefits in the way we think and act, but that does not mean that it exists as an entity.

Now, here's Will Wilkinson explaining his problem with that (he uses the word "eliminativism" where I use "reductionism"):

Right off, I get red flags. Eliminativism of all sorts -- about morality, consciousness, free will, the self -- is frequently motivated by what I like to call the “fallacy of disappointed expectations.” The heart of the fallacy is to accept at the outset that the nature of the self, for example, is precisely what an extravagantly metaphysical, often religious, account says that it is. Then one observes that there exists little or no evidence in support of that account. One then concludes, having already simply assumed that the self (or free will or consciousness or moral reasons) could not be something less grand, that there is no self (or free will or consciousness or morality). If the self isn’t a hard gem-like flame literally flickering somewhere east of the pancreas, then there is no self! Usually arguments from disappointed expectations are advanced in a spirit of excited, self-congratulation, as if reasoning poorly were the same thing as staring bravely into the abyss.

I strongly agree with Wilkinson — about the self and all his other examples (free will, consciousness, morality). He's articulating something I've noticed before, but I hadn't thought to put it in terms of "disappointed expectations."

When I was in college, I had a philosophy professor who seemed frustrated by the fact that many students wouldn't give the obviously correct answers to the most basic moral hypotheticals (e.g. whether it's morally better to care for a sick person or to eat babies). He said something to the whole class that was startingly rude but hard to deny: "The intelligence level tends to get turned down in philosophy classes."