As to "inherent lack of quality," I think you'll be hard pressed to find many professors who prefer 20,000 word answers with objectively deeper analysis to 5,000 word answers that hit all the same issues but offer more "pruned" analysis (e.g., dismissing claims that have no real chance of succeeding in one sentence instead of five). Call me cynical, but I think most of them prefer answers that are easier and quicker to grade.
This post is going to come off as bragging. I don't mean it to--I really don't--I just see this as a common misperception, and I want to offer a specific rebuttal.
In my experience, this isn't true. Professors specifically told me that my depth of analysis is what put me in the A+ level of things. That happened on every exam without a word limit in 1L (I did speak with the profs about the exams, since they were writing letters for me.) One professor in particular said "This is the highest grade I have ever given on any exam. You scored this high because the analysis makes the exam read like a brief." All of my exams had extra points allocated for depth of analysis and for spotting fringe issues (within my in-depth analysis of main issues) that weren't on the checklist.
If that had just happened in one class, I would be more willing to write it off, but three different professors (in four different classes--I had the same prof for Civ Pro I and II) thought the same way. One professor--who gave me my lowest 1L grade because I went 2,000 words over the word limit, and spent well over an hour trying to cut things--admitted to me that he didn't see what I would have been able to cut without losing substance.
On exams without word limits, I was adding things until the buzzer that netted points. On exams with word limits, I had at least an hour, if not more, to go back and make edits/pare things down (worked out well, except for the class I mentioned above.) The sad truth of it is that typing speed does matter--and it matters a *lot*, though certainly less in word-limited exams. Ironically, torts was one of my word-limited exams (and one of my courses with the narrowest scope,) which just goes to show that this isn't a subject-matter thing, it's an exam format thing.
I would say that the only exam format where speed doesn't matter a lot is a word-limited take-home.