I would argue that my Math degree made me a "better" writer than my Philosophy degree did. Writing quality in philosophy is generally much poorer than other disciplines; you pretty much have to use passive voice everywhere, which is the first thing your college writing lab will tell you not to do.
On the other hand, in my Math classes, I had to turn in 5-10 pages of proofs every week/every other day for problem set work. It was this work that taught me how to write clearly and parsimoniously, much more so than my Philosophy courses.
Of course, YMMV.
As a computer science major with a philosophy minor, I personally found my philosophy minor much more useful in learning how to write clearly than my CS major was.
[1] Arbitrarily chosen example from a recent abstract http://mind.oxfordjournals.org/content/125/499/627.abstract
For what it's worth, I don't think undergraduate CS degrees develop students' writing abilities at all. There are only a few proof-based courses I can think of, and those courses (e.g., Theory of Computation, Algorithms) need not necessarily be taught in a mathematically rigorous manner (which is to say, proof writing in these courses may be minimal, depending on the instructor).
[0] http://wehaveneverbeenblogging.blogspot.com/2010/02/on-activ...
Edit: grammar!
And at any rate, I don't believe I ever claimed that a Philosophy degree was the best way to develop your writing.
This poor writing is certainly not limited to any particular philosophical discipline, or even to philosophy in general. Math and science tend to be just as bad (often even much worse, except sometimes on the issue of clarity -- at least as far as their intended audience is concerned).
I think the common laborous style comes from the desire to seem "objective", the tradition of presenting very long, drawn out arguments in a "logical" fashion, and the attempt to efface the author from the work (so as to make the argument seem to be self-evident given the premises, and not at all biased or based on one person's experience or opinion). That's hard to do in an engaging manner.
More recently, the practice of revealing who the author is and where he stands is starting to become a little more common. That helps to make the writing more engaging and helps the reader to make more of a connection with the author, but I think this still is very much a minority style. Most of philosophical writing is still mired in "objective" style, and it's difficult to foresee when or if it'll ever make it out.
PS: I'm guilty of this myself, and should really take some writing courses! :)
I think this reflects a common misunderstanding about either philosophy or what constitutes a "transferable skill." Philosophy teaches writing (quite intensively, in a good program) and abstract analytical skills. I have a philosophy degree and not only have I found it valuable, prospective employers have too. This especially true in my field (law), but I have heard it is true in others as well.
Of course, your experience will vary depending on the type of jobs you're looking at. Some industries will expect specific concrete skills that a philosophy degree will not teach you. And others will tend to be less populated, largely for cultural reasons, by people who understand its value. But this is no different from any other area of study: you have to have some idea of what you want to do in order to determine what field of study would be helpful.