And given the incredible richness of so many of the thinkers, I think this whole era is unduly neglected by non-historians. For that matter, given the scholarship Leiter mentions, it seems indefensible to me that so many departments stop the undergraduate history requirement with Kant.
For a very long time I thought that in fact it was standard in undergraduate philosophy departments to teach at least some 19th century German philosophy; it wasn't until I came out of graduate school and started looking at what departments were offering that I realized that this end-at-Kant thing is disturbingly common. The reason I was subject to this misapprehension was that in my own undergraduate education, which more and more I have come to think of as truly exceptional, I did get 19th century German philosophy -- Schiller and Hegel, in particular -- in the Continental Philosophy class (which, although it did get into 20th century continental mostly focused on antecedents, which I think was probably wise), taught by Jeff Gauthier. In no way can such an exposure give one an adequate understanding of Schiller or Hegel, but this is true of Kant (or, indeed, most others), as well, whether we choose to admit it or not; the thing that matters is that it was an exposure, and a direct exposure, a light but real immersion. Undergraduates can never navigate the ocean of a Hegel, but they can swim and surf a bit at some nice beaches. Such an exposure is invaluable.
Indeed, if anything, I think it's unfortunate that 19th century philosophy is virtually synonymous with 19th century German philosophy; British philosophy in particular has traditionally been heavily shortchanged, with Bentham and Mill alone getting mentions for their ethics -- which apparently just hangs in a void rather than being (as it really was) part of heated debates with intuitionists of all stripes and connected to everything from philosophy of law to philosophy of science to natural theology.
But, of course, in a sense this deficiency is just a symptom of a deeper problem, which is that history requirements at the undergraduate level are in general utterly inadequate, leading to vast and demonstrably important (in terms of influence) regions of philosophical history (Middle Platonism, Neoplatonism, most of scholastic philosophy outside of Aquinas, German Idealism and to an even greater extent British Idealism, etc., etc.) being filled in with the words "Here Be Dragons" (if even that) -- and thus leading to professional philosophers whose conception of the history of philosophy is a caricature and cartoon, who in turn propagate their flat-earth conceptions of philosophical history to new generations.