I have a Moshi Clearguard because I have a Siberian Husky dog, and don't like intense amounts of hair getting stuck under the keys, and it really isn't that bad.
It takes a day or two to form a good fit over the keyboard it seemed, that or I just got used to it a lot more. After that, it barely messes with my typing, if at all. My keys feel a tiny bit more stiff and mushy, but it's not uncomfortable, and I write A LOT of papers and notes.
Other than massive amounts of hair getting stuck under the keys (no amount of vacuuming ever stops it), I don't see the problem. I don't mind shiny keys, it's not a major aesthetic issue anyways, and it's sad that some people protect their computers this much. It's a computer, it doesn't have feelings.