The skeumorphism in Reason is so over-the-top – there's a physics engine in there! - that it gets you in the right mindset: it's playful, it doesn't take itself seriously, and that's exactly what you need to get making music. It's exactly the opposite of WriteRoom because it's serving a very different mindset.
Even during my education, wherein I dealt with more than a few individuals in Reason's "target market" (see: aging film composers who have spent their fair share of time plugging real cables into real sequencers) found it appalling and difficult to use.
The only reason I still use the program at all is because it has a few excellent patches built into it. The fact that I have to wade through the swamp of illogic that is its user interface remains one of most frustrating parts of my job as a media composer.
But there is no such thing that I know of (in Reason4), so without a physical MIDI control surface you're effectively lost.
Disclaimer: I'm only a casual Reason user, perhaps I'm missing something. I also hear Reason5 has some improvements but haven't upgraded yet.
Same with iBooks. I know people who love the faux-3d book pages and who swear it enhances the experience for them. Perhaps the author has a point about them not being proportional but that would be a suggestion to make the effect more useful. Not a reason not to use it.
Skeumorphic design elements are, by definition, decorative elements that CAN enhance functionality. So even if they don't enhance functionality they're still acceptable as long as they don't impede it.
There's a point where minimalism is as much a fetish as draping everything in ornate gewgaws, I think.