For the last 20 years (and well before that for all I know which I don't) every high profile reformist commission/panel/whathaveyou that has looked at legal education has come to pretty much the same conclusion: law schools don't teach people much if anything about practicing law, and they should do something about that. Of course lawyers have been saying the same thing for even longer, although in the typical fashion of this business, the fancier law firms, who in theory could use their hiring policies to make the fancier law schools behave differently, have never done anything to put any real pressure on such schools to engage in more vocational education.
Why do law schools engage in so little vocational training? Let's consider the vocational training, loosely speaking that does happen in the contemporary law school. This takes three forms: clinics, legal research and writing courses, and more traditional courses that are designed to have what is now being called an "experiential" component.
Clinics are very expensive, and at most schools remain relatively low-status entities. Clinical professors are often non-tenure track, and schools tend to have strict limits on the number of clinical courses students can take. This is in part because clinics aren't considered academically serious by lots of both traditional doctrinal and "law and" faculty, and in part because at most schools the carrying capacity of the clinics is limited enough that it would be impossible for every student to take even one clinic over the course of his or her law school curriculum. (Again, clinics are very expensive). The biggest problem with any serious emphasis on clinical legal education is that it threatens to raise all sorts of uncomfortable questions about the rest of the law school experience. If law schools start looking more like culinary institutes (in which students pretty much do nothing but cook all day) then doesn't it make sense to de-emphasize the overtly academic side of the enterprise altogether, and move more explicitly, as is the case in so many other legal systems, to a post-college apprenticeship model of some sort? This is obviously a question that the contemporary legal academy would prefer not to even entertain, let alone answer.
Legal research and writing courses are also expensive, although less so than clinics, because of low faculty student ratios. They are also low status (a pattern is developing here), and are generally taught by non-tenure track faculty. Lawyers love to complain about how freshly-minted law graduates can't write, and no doubt many can't (of course huge numbers of long-time practicing attorneys and judges can't write either). The problem with teaching law students how to write is that it's almost impossible to do anything about students' basic writing ability by the 18th year of their formal education. By that time either you can write well or you can't,and nothing is going to change that. Now there's the narrower technical matter of teaching specifically legal writing, but learning legal writing, like all other writing, is almost completely a matter of imitation through practice. (That is, when it consists of something more inspiring than cutting and pasting proper nouns from one document into another and having that work billed out at $400 an hour).
As for traditional courses, one reaction to the Carnegie Foundation report has been to begin to put more evidence on so-called "experiential learning" in the classroom (this is a misnomer, as in education theory "experiential learning" means, not surprisingly, learning through direct experience of the thing one is learning about). I'm skeptical about the the extent to which classroom simulations of trials, negotiations, and the like can have practical value, given the vast differences that must exist between simulations and the real thing. (Perhaps the most obvious example are trial advocacy courses in which, for instance, the witnesses are working off a script. In a real trial people are constantly going off script as it were).
Anyway, the biggest problem with experiential learning courses taught by tenure-track faculty couldn't be more obvious: the vast majority of tenure-track professors have very little practice experience, and in many instances what little experience they do have is at this point largely outdated. The other big problem with doing vocational training within the context of an academic unit of a university is that it's almost certain to be wildly inefficient. For one thing, lawyers do a vast array of professional tasks, although from watching TV and going to law school one could easily get the impression that they really only do one: Preparing for and then appearing in court. Beyond that, both the substance and the economic structure of the various kinds of legal practice is always changing, and never more rapidly than at present. As Bruce MacEwen points out, "the future is almost certain to unfold in ways that will mock any [vocationally-oriented education] scenario we could come up with."
Law schools as they are currently structured can't deliver significant amounts of vocational training at all, and it's difficult to envision how they could be restructured in a way that would allow them to do so at a reasonable cost to their students, especially if they were to remain academic units within research universities. At bottom, the problem with trying to teach practice within a university setting is that the best and most cost-effective teacher of practice will always be practice itself.