"Market microstructure" covers a fair amount of ground imho. I think it is a valuable area of study but unfortunately have seen a very small number of studies that i actually found helpful. I think people use concepts from the field unknowingly all the time. For example: Consider the debate on another thread about what is an ideal tick size for the ES contract. This raises a lot of questions that can eventually lead to a better understanding of how markets work. What effect does a tick size that is large relative to daily range have on volatility? on liquidity? What effect does a FIFO matching engine have vs. Pro-Rata on trading? Volatiility? Liquidity? What effect do the relative sizes of clearing/exchange fees have on Vol, liquidity, etc... What about the speed with which the exchange publishes market depth? What about the communications infrastructure used? Do breakout strategies work better in thick deep markets or thinner markets? What about fading strategies? If i need to get into a 100,000 contract position what is the most efficient (ie. least slippage/market impact/disguised) method to do so? These are the kinds of questions that people try to study in market microstructure. The don't always do a good job, and sometimes from the assumptions the authors don't show much "street" sense. But that isn't always the case and even so it doesn't mean that there aren't a lot of useful questions that you can answer for yourself through study.
Here's the book I used when in school. Actually, I had it as a collection of lecture materials. Harris got the book published from the lecture material way after I left. http://www.amazon.com/exec/obidos/tg/detail/-/0195144708/103-9387028-1585440?v=glance Knock yourself out.
Never read this book. However, I think there is a difference in that it concerns market mechanics, while market microstructure studies equilibrium theories regarding information, volumes, etc. Market microstructure is a subfield of financial economics, not a simple characterization of how markets operate.
They got their degree awarded by a jury (sometimes sloppy), not by the market (never sloppy). Marketwise, PhD's come like ordinary people do: a few bright ones and many dumb ones. Most PhD's love to jabber about things they really don't know much about, just like the common guy.